Testing infra updates

use hash storage to save/retrieve files

fix uploads of small files

Integrate travis, add badges and coverage

cgi.FieldStorage by default doesn't use make_file.
Only if the file is bigger than 1000 bytes the method is called.
Overriding the private method __write allows to always call the method
independently of file size.

closes #88

Cache testdata download

More job fixes

Paste script improvements

We don't want to interfere with a system-installed mongod.

Job rules

Sanitize filepaths