Add shift; several error messages displayed to user at once

[sebjimenez]

• When adding a new shift several error messages are displayed to the user at once when the format is incorrect. Should be less messages and better explained.

[chargio]

Would you propose to delete the flash or the messages? Messages are nice as they explain what is going on, perhaps adding them to the form code (inline as in patternfly) would make it easier:

• red box around the error
• error message below the error explaining it