Get the username and server from course info in login.

[Salmela]

Closes #326

[coveralls]

Coverage increased (+0.06%) to 75.829% when pulling 5493346 on ask-only-password-in-courses-aleksi into 8909732 on master.

[coveralls]

Coverage increased (+0.06%) to 75.829% when pulling eb44a8d on ask-only-password-in-courses-aleksi into 8909732 on master.

[coveralls]

Coverage increased (+0.05%) to 75.94% when pulling 2b799c8 on ask-only-password-in-courses-aleksi into d19475c on master.

[coveralls]

Coverage increased (+0.05%) to 75.94% when pulling dd13c8c on ask-only-password-in-courses-aleksi into 3cf1d53 on master.

[coveralls]

Coverage increased (+0.05%) to 77.021% when pulling c3d84ef on ask-only-password-in-courses-aleksi into 1cd105b on master.

[mikkomaa]

LGTM.