Fixed several issues regarding account login

...java/de/kuschku/quasseldroid_ng/ui/chat/MainActivity.java

...chku/quasseldroid_ng/ui/chat/chatview/MessageAdapter.java

...uschku/quasseldroid_ng/ui/chat/fragment/ChatFragment.java

...ava/de/kuschku/quasseldroid_ng/util/accounts/Account.java

...kuschku/quasseldroid_ng/util/accounts/AccountManager.java

...u/quasseldroid_ng/util/accounts/AccountManagerHelper.java

app/src/main/res/layout/widget_core_account.xml