Improve Checker#checkDirectory method

Make it aware of "fileExtensions" option

Ref #445
Place fileExtensions fixtures on right path
Fix recursive descend

* Break down "_shouldProcess" method to two private methods

* Simplify checker module, it contradicts original code idea
but it easier to read

* Add tests for checker module

Fixes #445
Closes gh-447
Improve requireSpaceBeforeBinaryOperators rule

Catch nodes with "VariableDeclarator" type
Improve disallowSpaceBeforeBinaryOperators rule

Catch nodes with "VariableDeclarator" type
Improve disallowSpaceAfterBinaryOperators rule

Catch nodes with "VariableDeclarator" type
Improve requireSpaceAfterBinaryOperators rule

Catch nodes with "VariableDeclarator" type
Prepare for version 1.5.2
1.5.2
Remove incorrect comment in cli module

jQuery preset is not the only preset anymore

Closes gh-450
Fix docs for "Removed Rules" section

disallowSpacesInConditionalExpressions -> disallowSpacesInConditionalExpression

Closes gh-449
Ignore ios instruments style imports

Temporary, until we will have inline rules

Closes gh-446
Remove merge artefact
Make test for "ios instruments" more "visible"
Add missing rules in jQuery preset

Fixes #452
Fix typo in warning notice of *stickedOperators

Per @mikesherov suggestion

Ref 9bf5b8fe445364d0abe1c9b20edcfedf300fc835
Exclude comma operator from binary rule

Since it's more pragmatic and
easier to use with "true" value of requireSpaceBeforeBinaryOperators rule
Prepare for version 1.5.3
1.5.3
Simplify cli module