fix thumbnail generation for allowing multiple project shots
display shot ID on interface
server error 500 display on dashboard
add 'failed' status for jobs and shots (also fixed jobs db update in server)
fix directory checking in dashboard /shot/<id>
fix error encoding on dashboard
Merge pull request #49 from msimoncz/dev

General development
Partial refactoring, REST API and testing

This commit is meant to introduce more order in the server codebase,
but some changes have been made to the dashboard as well. It should not
introduce functional changes.