Resolve "login screen - login component logic" - fix

Closes #57

See merge request swtp-block-ws17/arsnova-angular-frontend!56

Create guestLogin method

Add check for valid email address as username

Resolve "login screen - password reset component logic"

Closes #49

See merge request swtp-block-ws17/arsnova-angular-frontend!53

Use angular-flex for form
Implement FormControl and Matcher

Resolve "login screen - register component logic"

Closes #55

See merge request swtp-block-ws17/arsnova-angular-frontend!51

Adjust form to use fxLayout
Add FormControl and Matcher

Resolve "participant home screen - html template (room)"

Closes #37

See merge request swtp-block-ws17/arsnova-angular-frontend!57

Add some more demo room data
Use Material's Card for room view
Add some more buttons
Add some simple stylings

Resolve "login screen - service" 2nd

See merge request swtp-block-ws17/arsnova-angular-frontend!58

Don't return observables in getter functions anymore as we're storing the user in a object we can return immediately.

Store and load user data so we don't lose the user's data on reload.

Added service handling local data. Use this service so we can change the used technology (cookie, local storage, ..) easily.

Resolve "HttpService - Error handling"

Closes #78

See merge request swtp-block-ws17/arsnova-angular-frontend!52