Fix validation of start_time to be less then end_time
Repair to start_time can be equal to end time
Resolve problem with DateTime.parse to validate start & end time
changed login redirection
added flash messages to sessions_controller
Merge pull request #23 from gotar/event_validate_fix

[#26] Event validate fix of start_time to be less or equal end_time
Merge pull request #24 from gotar/login_redirection

changed login redirection
[#38] Again merged with master