Support mongoDb replica sets and local mongo _id

Use URIParser to create connections so that connections to either a
single mongo db or a replica set are supported. A replica set connection
is required in order to be able to keep inserting documents in the
replica set when the master fails over.

Add an option to automatically generate a mongo _id field using the
event timestamp when inserting a document.
Grok does create field when pattern matches all message

As of today grok filter does not create a specific field
if the grok matches the whole message. This commit changes
this behavior and make grok create the required field in
the configuration file
Allow repeating a field in the hash config . Fix LOGSTASH-919
add alternative tags on grokparsefailure
Allow empty arrays as values in grammar
range filter
some doc changes
rough first draft of metaevent filter
checkpoint
working proof of concept
fixed tag adding
@message was missing in event, added 'Message' field to @message.
field_remove option in base filter + fields are arrays only if they have more than one value
s/min/max/ typo
filter based on field names too + any or all match logic
statsd don't send event which are older than specified number of seconds
TyPo
Create cipher.rb

Adding a new filter. Cipher goal is to provide on the fly event content encryption and decryption. Beware of CPU cost.
New filter plugin "Advisor"
Merge branch 'master' of github.com:Spredzy/logstash into Spredzy-master

Conflicts:
	spec/filters/grok.rb