Merge

Better handling of negative indexes (Fixes #15)

Fixing regular expression in QueryMatchFilter to match single charact…

…ers ie. 1 (Fixes #12)

Adding implicity PHP 5.4 requirement to composer.json (Closes #8)

Adding and fixing "not equal to" filter

Lexer clean up and refactor

- Added JSONPathToken class as value object
- Updated the lexing and filtering of the recursive token ("..") to allow for a combination of recursion
   and filters, eg. $..[?(@.type == 'suburb')].name

Merge pull request #5 from twistor/fix-simple-access

Fix simple key usage (expressions are not required to start with "."). Allow expressions to start with "0". Move expression sanitizing to lexer.

Better empty/null checks for first and last methods

Fixing first & last methods