Resolve "Re-check template layout"

Closes #73

See merge request swtp-block-ws17/arsnova-angular-frontend!32

Resolve "login screen - login component logic"

Closes #57

See merge request swtp-block-ws17/arsnova-angular-frontend!31

Add usage of angular flex classes and properties
Use fxFlex to fill all available screen space
Remove old scss properties which are no longer used

Remove unnecassary redirect on login failed
Add ngSubmit functionality to enable keyboard submit

Resolve "comment creation - participant model"

Closes #44

See merge request swtp-block-ws17/arsnova-angular-frontend!26

Resolve "login screen - service"

See merge request swtp-block-ws17/arsnova-angular-frontend!27

Resolve "room creation - HTML Design (form)"

Closes #25

See merge request swtp-block-ws17/arsnova-angular-frontend!22

Implemented route guard that can be used to protect routes from access by not logged in users.

Resolve "Error page"

Closes #66

See merge request swtp-block-ws17/arsnova-angular-frontend!17

Resolve "login screen - page"

Closes #65

See merge request swtp-block-ws17/arsnova-angular-frontend!18