Adding test to verify SQL generation with an expression in `COUNT()`
Allowing expression in `COUNT()` DQL aggregation functions
Adding DDC-3276 test group
DDC-3276 - #1122 - updating EBNF in docblock to reflect new syntax support
DDC-3276 - #1122 - updating EBNF in documentation to reflect new syntax support
Merge pull request #1122 from Ocramius/feature/support-arithmetic-expressions-in-count

Support arithmetic expressions in `COUNT()`