feat: Added approve method for Mergerequests - #685

I have added the unapprove method and I have put the parameters on one line, added default value for sha. I could not find the pep8 errors about double missing blank lines? (I ran tox locally against my branch).

@gpocentek Travis is not reporting back and I don't see the build in the UI. Do you have any way to restart it?

I am not very familiar with travis, I have closed and reopened the pull request. That should trigger another build?

A force push would trigger another build. But I think @gpocentek should be able to restart it manually.

I can't see the build on travis.

@Joustie Do you mind doing a rebase and a push --force? Thanks!

@gpocentek I have made sure the travis builds succeed for my fork, and rebased and pushed --force but still the checks are not updated? Maybe try a brandnew PR?

@Joustie I'm sorry that travis is misbehaving. I think we should merge it. Tests pass locally for me.

@Joustie Could you do a rebase and then @gpocentek could merge it. (not sure, if I could as CI is failing)

@Joustie the changes look good and we'll merge without travis, but there are merge conflicts that need to be resolved first. Could you have a look at that?

Thanks!