Release 1.0.0

Added

• Merge support (#96)
• Set PHP 5.5.9 as minimum required version (#75 and #99)

Fixed

• Fix PHP 5.6 test (#100)
• Edit PHP versions tested on Travis (#101)
• Add more info about the symfony/yaml requirement (#97 and #102)

Breaking changes

• PHP 5.3 and 5.4 are no longer supported.