Refactoring and creating a method to test authentication.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15803 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Test saved credential before returning it.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15804 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Renaming the buttons as per IGBD-391

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15805 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Check that the mirror server url length is greater than zero.

git-svn-id: https://svn.code.sf.net/p/genoviz/code/trunk@15806 80d5a9c2-7d8c-4c9f-9369-4e03bca4d2bd
Merge remote-tracking branch 'upstream'