Add solium linter (#39)

* add solium configuration and list command

* run lint with fix

* fix lint errors and warnings and add pre-commit lint hook

* remove useless npm script

* change max-len rule to error

* change all warning rules to errors

.soliumignore

@@ -0,0 +1,2 @@
+node_modules
+contracts/Migrations.sol

.soliumrc.json

@@ -0,0 +1,17 @@
+{
+  "extends": "solium:all",
+  "plugins": ["security"],
+  "rules": {
+    "error-reason": "off",
+    "indentation": ["error", 2],
+    "max-len": ["error", 99],
+    "no-constant": ["error"],
+    "no-empty-blocks": "off",
+    "quotes": ["error", "double"],
+    "uppercase": "off",
+
+    "security/enforce-explicit-visibility": ["error"],
+    "security/no-block-members": ["error"],
+    "security/no-inline-assembly": ["error"]
+  }
+}

contracts/AnchorRegistry.sol

@@ -1,47 +1,85 @@
 pragma solidity ^0.4.24
 ;
-import 'openzeppelin-solidity/contracts/ownership/Ownable.sol';
+
+import "openzeppelin-solidity/contracts/ownership/Ownable.sol";
+
 
 contract AnchorRegistry is Ownable {
-	event AnchorRegistered(address indexed from, bytes32 indexed identifier, bytes32 indexed rootHash, bytes32 timestamp, uint anchorSchemaVersion);
-    struct Anchor {
-        bytes32 identifier;
-        bytes32 merkleRoot;
-        bytes32 timestamp;
-        uint schemaVersion;
-    }
-
-    mapping (bytes32 => Anchor) public anchors;
-
-    function registerAnchor (bytes32 identifier, bytes32 merkleRoot, uint anchorSchemaVersion) public {
-
-        //not allowing to write to an existing anchor
-        require(anchors[identifier].identifier == 0x0);
-
-        // not allowing empty string
-        require(identifier != 0x0);
-        require(merkleRoot != 0x0);
-
-        // not allowing "null"
-        // some clients will translate a *null* to a string containing "null" 
-        // reject this to prevent coding errors on the user side
-        require(identifier != 0x6e756c6c00000000000000000000000000000000000000000000000000000000);
-        require(merkleRoot != 0x6e756c6c00000000000000000000000000000000000000000000000000000000);
-
-        require(anchorSchemaVersion > 0);
-
-        bytes32 timeStamp = bytes32(now);
-
-        anchors[identifier] = Anchor(identifier, merkleRoot, timeStamp, anchorSchemaVersion);
-        emit AnchorRegistered(msg.sender, identifier, merkleRoot, timeStamp, anchorSchemaVersion);
-    }
-
-    function getAnchorById (bytes32 identifier) public view returns(bytes32, bytes32, bytes32, uint) {
-        return (
-            anchors[identifier].identifier, 
-            anchors[identifier].merkleRoot, 
-            anchors[identifier].timestamp, 
-            anchors[identifier].schemaVersion
-            );
-    }
+  event AnchorRegistered(
+    address indexed from,
+    bytes32 indexed identifier,
+    bytes32 indexed rootHash,
+    bytes32 timestamp,
+    uint anchorSchemaVersion
+  );
+
+  struct Anchor {
+    bytes32 identifier;
+    bytes32 merkleRoot;
+    bytes32 timestamp;
+    uint schemaVersion;
+  }
+
+  mapping(bytes32 => Anchor) public anchors;
+
+  function registerAnchor(
+    bytes32 identifier,
+    bytes32 merkleRoot,
+    uint anchorSchemaVersion
+  )
+  public
+  {
+    //not allowing to write to an existing anchor
+    require(anchors[identifier].identifier == 0x0);
+    // not allowing empty string
+    require(identifier != 0x0);
+    require(merkleRoot != 0x0);
+
+    // not allowing "null"
+    // some clients will translate a *null* to a string containing "null"
+    // reject this to prevent coding errors on the user side
+    require(
+      identifier != 0x6e756c6c00000000000000000000000000000000000000000000000000000000
+    );
+    require(
+      merkleRoot != 0x6e756c6c00000000000000000000000000000000000000000000000000000000
+    );
+    require(anchorSchemaVersion > 0);
+    // TODO remove this
+    /* solium-disable-next-line */
+    bytes32 timeStamp = bytes32(now);
+
+    anchors[identifier] = Anchor(
+      identifier,
+      merkleRoot,
+      timeStamp,
+      anchorSchemaVersion
+    );
+
+    emit AnchorRegistered(
+      msg.sender,
+      identifier,
+      merkleRoot,
+      timeStamp,
+      anchorSchemaVersion
+    );
+  }
+
+  function getAnchorById(bytes32 identifier)
+  public
+  view
+  returns (
+    bytes32,
+    bytes32,
+    bytes32,
+    uint
+  )
+  {
+    return (
+    anchors[identifier].identifier,
+    anchors[identifier].merkleRoot,
+    anchors[identifier].timestamp,
+    anchors[identifier].schemaVersion
+    );
+  }
 }