Created ProblemListActivity to display problems.
Display problem with fake data in ServerConnection.
Added string value for account, password, and submit.
Added progress bar while waiting problem list from server.
Changed TAG from string to class name.
Changed task completed result to raw json string.
ServerConnection won't process the json string anymore, it just passes the result.
Done listing problem list from server.
Removed redundant server task classes.
Refactored serverConnection.
Merge branch 'problemList'

Conflicts:
	res/values/strings.xml