Support for pipelines

This mr refers to #11 (closed)

It supports fetching the status of pipelines from Gitlab.

Exmaples

List all pipelines

$ git lab pipeline
#63472  support-for-pipelines  a minute ago  pending
#63002  support-for-pipelines  4 days ago    success

Get specific pipeline by ID

$ git lab pipeline 63472
Pipeline #63472 for support-for-pipelines triggered by Leon Morten Richter(leonmorten) 2 minutes ago is currently pending

Filter by status

$ git lab pipeline --status=success
#63002  support-for-pipelines  4 days ago  success

# or

$ git lab pipeline --status=pending
#63472  support-for-pipelines  3 minutes ago  pending

# or
$ git lab pipeline --status=failed
...

List pipelines for given reference

$ git lab pipeline --ref=support-for-pipelines
#63472  support-for-pipelines  4 minutes ago  pending
#63002  support-for-pipelines  4 days ago     success

Chain different options

# List all pending pipelines for the current MR
$  git lab pipeline --ref=support-for-pipelines --status=pending                                                            #63472  support-for-pipelines  5 minutes ago  pending