fixes #38. large file uploads

- increase limit to 20MB
- configure nginx limits
- tweak UI to display limit
Merge pull request #41 from tanmaykm/tanmaykm

fixes #38. large file uploads
added JuMP solvers
added cpu limit configuration.

also, hostname in container set to juliabox
handle expired/revoked google auth tokens. fix #42
Merge pull request #43 from tanmaykm/tanmaykm

Multiple changes/fixes