Only repopulate memcached if no error with #get
this catches the error for whitespace in a get call
populateMemcached takes a key and value
Use key, not username when retrieving session form memcached
Store session data in memcached against key, not username
setMemcachedData must come before setUserMetadata
Added backend and frontend validation for username registration
Fix regex
Merge pull request #1353 from jsbin/fix/1352

Only repopulate memcached if no error with #get