Fix #919 - file locking exception sometimes seen when testing upload package with local file system.
Revert "Issue #875. Add a DB index to boost performance of the common 'user by authenticated username' query. Limit max username size and other string sizes for Users."

This reverts commit cc09ad19f5926820975b76c351c53038b1fb202a.
Merge pull request #921 from NuGet/tilovell-919

Fix #919 - file locking exception sometimes seen when testing upload pac...
Merge branch 'dev' into preview