[Issue #80] finished implementation and documentation of username or email signin
[Issue #80][Finished] Fixed code conventions and update uml
[Issue #80][Finished] fixed conflicts for master merge
[Issue #80][Finished] fixed documentation conventions
[Issue #80][Finished] fixed uml arrow spacing
[Issue #80][Finished] fixed code conventions.. again
[Issue #80][Finished] fixed code conventions in tests
[Issue #80][Fixed] removed two extra new lines at the end of file
Merge pull request #387 from MGhanem/c1s8_adamggg_signin_sprint2

[Issue #80] finished implementation and documentation of username or email