ignore Composer-related files
Merge pull request #150 from greg0ire/version_control

ignore Composer-related files
use more appropriate words
grammar
use words
ease pronunciation
whitespace
Merge pull request #152 from greg0ire/documentation_improvements

Documentation improvements
coding style
quote the block type

This happened to me :

- the block type was null
- the message was :
   > The block type does not exist

A better message would be :
> The block type "" does not exist
Merge pull request #155 from greg0ire/error_message_improvement

Error message improvement
Merge remote-tracking branch 'sonata-project/master'

Conflicts:
	.gitignore