Doc:

• Update .travis.yml #171
• Fixes in php doc blocks #174
• Php doc fixes #176
• Symfony 4 ready #177
• Fix typo #191

Fixes:

• Fix a bug in the lime unit-testing lib #168
• Fix error 'A non well formed numeric value' on sfValidatorFile #181
• Fix usage of octet in recent patch #182
• Allow PATCH as an option in functional tests #185
• Fix case for isSubclassOf method #189
• Remove typehint from exception handler #188
• Fix counting of non-countable var for PHP 7.2 #178