Show a dialog to request username and password to the user on authentication request
Show alert message when user or password in authentication is not correct
Create dialog fragment for showing authentication dialog
Fixed bug it is not possible to login using two accounts in saml server. Clear webview cache.
Merge branch 'develop' into ADFS_auth_support

Conflicts:
	res/values/strings.xml
Changes after CR
Merge pull request #614 from owncloud/ADFS_auth_support

ADFS IdPs support added to SAML authentication