[RSPEC] Refactoring step 1

- Move helper functions in own modules and extend Rspec
- Refactor files into correct naming and paths
- Modify files to use new spec_helper and helpers
- Pin rspec to 2.14.x

Fixes #1758
Update gitignore file

Fixes #1758
Add missing tests

Fixes #1758
An other missing one

Fixes #1758
Fix performance tests

- date speed test only run when performance is enabled

Fixes #1758
[TESTING] Fix tcp input spec test

Fixes #1758
[TESTING] Fix Kafka output test

When doing randomized testing, one of the tests failed because kafka was not initialized yet

Fixes #1758
Minor fixes after review

Fixes #1758
[TESTING] Convert ruby filter spec after rebase

Fixes #1758
remove kafka source since they moved to separate plugin
Closes #1801
#1791: Merge with upstream elasticsearch/logstash and fix conflict