EDMA v0.1.0-beta.5: Add Sled support

[chungquantin]

Changelog

• Migrate from fixed column family design to TagBucket datastructure
• Allows more databases to be integrated into EDMA using TagBucket
• Supported tags: tree (for Sled), column_family (for RocksDB)
• Add Sled integration: Allows iterate and view database item stored globally and stored in a tree using command TREE=<tree_name_goes_here>

New Features

Check the latest version of EDMA: https://crates.io/crates/edma

Support sled database (request in this PR: https://github.com/nomadiz/edma/issues/8).`sled` database is one of the most popular databases in Rust ecosystem. sled is a high-performance embedded database with an API that is similar to a BTreeMap<[u8], [u8]>, but with several additional capabilities for assisting creators of stateful systems.

It is fully thread-safe, and all operations are atomic. Multiple Trees with isolated keyspaces are supported with the Db::open_tree method.

This integration allows developer to view data stored globally or in isolated keyspaces (tree) in sled using EDMA.

How to use sled with EDMA?

With a simple additional line in your current JSON configuration file. sled is fully embedded.

{
  "databases": [
    // ...other databases
+  {
+    "name": "sled",
+    "path": "../temp/cf"
+  },
  ],
  "templates": [
	// ...other templates
  ]
}

[edwardwc]

Looks awesome -- look forward to using!