PLFM-(2195-2197) Begin wiki history service support

-Create database table for snapshots of markdown
-Update other tables to support history service
-Create v2 of the wiki page's DAO
Merge branch 'develop' of https://github.com/Sage-Bionetworks/Synapse-Repository-Services into wikiHistory
Edit method call for the change in the basicDao's methods after merging
Merge branch 'develop' of https://github.com/Sage-Bionetworks/Synapse-Repository-Services into wikiHistory
PLFM-2117; service layer
Created tests for the v2 wiki page DAO and changed DAO logic as needed
Clean up unused code
PLFM-2117
Clean up unused code
Removed new migration types to pass tests and check in progress
PLFM-2117
PLFM-2117
Merge branch 'develop' into PLFM-2117
Merge pull request #717 from heidiso/wikiHistory

Starting services for the Wiki history
PLFM-2117 synapse client
PLFM-2117; integration tests
PLFM-2224: create text previews for sh and js files
PLFM-2117: ensure limit, offset have right order
Merge pull request #722 from jay-hodgson/PLFM-2224

PLFM-2224: create text previews for sh and js files
Increase timeout of a worker test