tag synonyms
model, management command, and test code
If tagsynonym tag1->tag2 exists when a user asks to rename tag3->tag1, abort

If tagsynonym tag1->tag2 exists when a user wants to rename tag2->tag3, update tagsynonym table

When create_tag_synonym creates a new target_tag, we copy source_tag's info to target_tag.
'Not sure if deleting this was a right thing to do as we don't want tags tag1 and TAG1 we always want a single case variant. If someone attempts to create a case variant we should auto-correct.'

reverting it
Merge branch 'pcompassion'
edited documentation and the contributors file