* [Slim] Add PHP CodeSniffer package
* [Slim] Add phpcsStandard generator option
We follow PSR-2 coding style guide in PHP generators. It might be convenient
for users to specify own coding standard without modifying templates. That's
why I've added this option.
At first, I thought to add option validation and accept only standards from
predefined list. But this option also can be a full path to the standard's
root directory, I've changed my mind. User should use this option with caution.
Ref to all PHP CodeSniffer CLI options:
https://github.com/squizlabs/PHP_CodeSniffer/wiki/Usage
* [Slim] Extend readme with PHP CodeSniffer docs
* [Slim] Format templates to meet PSR-2
* [Slim] Refresh samples
