Add coveralls badge to README

[themalkolm]

• Add coveralls badge to README
• Shielded both badges via http://shields.io to keep the same style

This gives and instant hint to a user where to find the coverage information.

[erikbern]

Cool. Unfortunately it's a bit embarrassing how low the coverage is right now :(

Maybe we should exclude luigi.contrib from the coverage? Or is this to game the system? :)

[erikbern]

Hm it looks like my coveralls commit has fucked up Travis – it's now running all tests multiple times. Let me fix

[erikbern]

Fixed it in 9ed55f5 – too lazy to send PR because it's an obvious bug

[themalkolm]

77% is low? Ha, ha. It is a quite a number especially if you take in account that some tests are simply disabled e.g. for ssh.

[themalkolm]

@erikbern Btw, as you are playing with coveralls you probably should check something like landscape https://landscape.io/github/themalkolm/luigi. Instantly gives some feeling about overall project's "health".

[coveralls]

Coverage remained the same at 76.74% when pulling 6df679c on themalkolm:patch-1 into ea8b59f on spotify:master.

[erikbern]

Cool is landscape for static analysis and style checking?

I set it up: https://landscape.io/github/spotify/luigi

[erikbern]

Yeah I guess 77% is acceptable (and there's 415 tests) but it would be great to get it up a bit more. Also some code is run through subprocesses (mrrunner.py etc) so it's slightly higher in reality. But we should aim to get it up to 85-90% and I think it's pretty easy