draft implementation of POST login
show a progress dialog during service signin
move http tasks in separate file
implement the rest client methods

TODO: remove duplication
initial login screen implementation
show toast message on login fail
make login a separate activity
save successful login state
parse and store cookie and CSRF token from login response
set cookies and CSRF token on requests
http profile action return a json object
store cookie and csrf data in settings

We implement a primitive cookie manager because we want to
support android 2.2 and above.

Android's cookie manager supports version >= 2.3 (API 9).

TODO: maybe move this in a separate class with separate settings name
call main activity on successful login
fix typo
show user email on main window view
move activity calls in functions
remove login form from history
remove onDestroy()
change string literal
add second application button