Make CyclopsApp/App configurable

The unused log_level argument was removed as a consequence.
Also, the options and handlers return objects are not returned by the
configure method anymore.
Fix pylint warnings
Take project key loading outside of tasks
Allow user to manually define a project list

Sometimes, the cyclops server might not have access to the sentry SQL
server where the project public secret keys are stored. In that case,
the user will want to manually define the list of project keys for which
the cyclops can act as a proxy. We defined the PROJECT_KEYS
configuration variable for that purpose.
Add configuration file generation utility

Also, update test configuration file and README.
Move mysql dependencies to extras_require
Allow multiple keys per project in PROJECT_KEYS

More than one pair of project public/secret keys may be generated for
each project. Also, project IDs should be manually defined.
Get rid of "weird travis python paths"
Merge pull request #9 from Polyconseil/optional-mysql

Make MySQL optional