Fix for issue #215

Add ‘esc_html_x’ Wordpress function to the EscapeOutput Sniff
Update EscapeOutputSniff.php

Add 'esc_html_x'
Extend to include other 'functions'

Extend sniff and unit tests to include ‘function’ language constructs
like empty() and isset()
Revert until released
Merge pull request #226 from mattyrob/master

Extend Sniff and Unit tests for issue #225