Added logic to throw clean ValidationErrors if name is not unique, but skip the rest as long as is_active==False - fixes #150. In the case where is_active==True, added smarter ValidationErrors to distinguish between bad API credential errors versus case where account name is not found in Twitter.
Removed TwitterUser.uid constraints blank=True,null=True; modified clean() logic to only validate for new TwitterUser (whether active or not) or for updating existing TwitterUser w/is_active=True. Allow duplicate names, but catch duplicate uid here.
removed 0025_auto__chg_field_twitteruser_uid.py
formatting tweak
merged conflicts between master and t150-skip-validation-for-inactive
Corrected dups.exclude to dups = dups.exclude, in order to actually modify dups and successfully exclude "self" from uplicate checks.
Merge pull request #152 from gwu-libraries/t150-skip-validation-for-inactive

Added logic to throw clean ValidationErrors if name is not unique, but s...