Allow to use a different remote for the pipeline

See merge request fatihacet/gitlab-vscode-extension!22

When you work using a fork the issue will be
associated with the origin project but your
pipeline will run in the context of the
fork project.

This commit allow user to configure a different
remote to watch their pipeline in order to
adapt to this workflow.

Ref #59

Allow to configure the remote

See merge request fatihacet/gitlab-vscode-extension!18

Remove url opening for Retry, Cancel and Create pipeline

See merge request fatihacet/gitlab-vscode-extension!20

Add notification on pipeline status change

See merge request fatihacet/gitlab-vscode-extension!21

This allows users to choose the git remote of his Gitlab project.

If no setting is provided, the previous behavior with auto detection is
kept.

Add CONTRIBUTING.md to explain developer instructions for new contributors

Closes #61

See merge request fatihacet/gitlab-vscode-extension!16

A new config option to toggle MR status on status bar

See merge request fatihacet/gitlab-vscode-extension!15

Fix messed-up link in CONTRIBUTORS.md

See merge request fatihacet/gitlab-vscode-extension!14

Fix messed-up link

See merge request fatihacet/gitlab-vscode-extension!13