Update gemspec
Add specs for RemoveLog service

Status code is debatable; I opted for 422 when the job is still
running, and for 500 if unexpected error happened
Update gems
Bring 'logs' table up to date

So that removed_* columns are added
Retry bundle install
Duplicate travis_retry()
Use bash function, not PowerShell
Add RemoveLog service endpoint to jobs/:id/log

This replaces https://github.com/travis-ci/travis-api/pull/107.
Standardize error handling for RemoveLog service endpoints

Return status 409 for errors
Clean up error handling for RemoveLog

With the error message change in travis-core, we can handle
2 exceptions in one rescue clause
DRY up log patching logic

Move the shared logic into a Helpers method so that there is no
code duplication
Tweak RemoveLog helper

Leave responding up to the endpoint
Remove unnecessary parameter from the helper's parameter
Update README [skip ci]

API now requires that `logs` table should be set up properly
Remove `PATCH logs/:job_id` endpoint

To eradicate unnecessary inconsistency.

Spec to test the existing `GET logs/:id` remains.
Merge branch 'master' into ha-feature-remove_log_endpoint

Conflicts:
	Gemfile.lock
	travis-api.gemspec
Bring travis-core up to date
Update gemspec
Merge branch 'master' into ha-feature-remove_log_endpoint
Update gemspec once again
Merge pull request #122 from travis-ci/ha-feature-remove_log_endpoint

Add RemoveLog service API endpoint