Tornado json

[ayushr2]

Resolves #8
Resolves #11 : If the preprocessing job fails, the entire run is marked as failed. Student jobs are not run. If any of the student jobs fail, the grading run is continued as normal.
Resolves #12 : Catches SIGINT and shutdown the system. Pending job poll calls are left hanging. The calls would eventually timeout and graders catch that and exit.
Resolves #13 : We do not have to worry about starting up mongo daemon anymore :)
Resolves #14 : We can configure each stage's timeout

[coveralls]

Pull Request Test Coverage Report for Build 100

• 313 of 377 (83.02%) changed or added relevant lines in 9 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+23.7%) to 83.544%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/database.py	14	16	87.5%
src/auth.py	35	42	83.33%
src/handlers.py	164	177	92.66%
src/utilities.py	27	46	58.7%
src/api.py	21	44	47.73%

Totals
Change from base Build 82:	23.7%
Covered Lines:	330
Relevant Lines:	395

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💛 - Coveralls