added dayofmonth and updated readme
updated readme for sf2: dayofmonth
added documentation for using palmasec/DoctrineORMServiceProvider and dflydev/dflydev-doctrine-orm-service-provider in order to register the custom functions in Silex
Merge pull request #5 from imbc/master

Added 'dayofmonth' Mysql function, updated readme and added section for usage with Silex