feat(all): replace bunyan library with js-logger library

replace bunyan library with js-logger library

docs/API.md

@@ -46,6 +46,7 @@
  *  [searchable](#searchable)
  *  [indexPath](#indexpath)
  *  [logLevel](#loglevel)
+ *  [logHandler](#logHandler)
  *  [nGramLength](#ngramlength)
  *  [separator](#separator)
  *  [stopwords](#stopwords)
@@ -598,7 +599,12 @@ The location of the datastore. If `db` is specified, then indexPath is ignored
 ### logLevel
 _string_
 
-A [bunyan](https://github.com/trentm/node-bunyan) log level.
+A [js-logger](https://github.com/jonnyreeves/js-logger) log level (can be lower or upper case - 'error' or 'ERROR').
+
+### logHandler
+_function_
+
+A [js-logger](https://github.com/jonnyreeves/js-logger) log handler function.
 
 ### nGramLength
 _number_ or _array_ or _object_

lib/index.js

@@ -1,4 +1,4 @@
-const bunyan = require('bunyan')
+const Logger = require('js-logger')
 const level = require('levelup')
 const down = require('leveldown')
 const SearchIndexAdder = require('search-index-adder')
@@ -64,12 +64,16 @@ const getOptions = function (options, done) {
   SearchIndex.options = Object.assign({}, {
     indexPath: 'si',
     keySeparator: '￮',
-    logLevel: 'error'
+    logLevel: 'ERROR',
+    logHandler: Logger.createDefaultHandler()
   }, options)
-  options.log = bunyan.createLogger({
-    name: 'search-index',
-    level: options.logLevel
-  })
+  SearchIndex.options.log = Logger.get('search-index')
+  // We pass the log level as string because the Logger[logLevel] returns
+  // an object, and Object.assign deosn't make deep assign so it breakes
+  // We used toUpperCase() for backward compatibility
+  SearchIndex.options.log.setLevel(Logger[SearchIndex.options.logLevel.toUpperCase()])
+  // Use the global one because the library doesn't support providing handler to named logger
+  Logger.setHandler(SearchIndex.options.logHandler)
   if (!options.indexes) {
     level(SearchIndex.options.indexPath || 'si', {
       valueEncoding: 'json',