Add project level MergeRequest API

Add support to rebase a merge request

Consistently use `SHA`

Improve OrderBy and Sort support for note lists

Merge Request Note Lists and Snippet Note Lists support OrderBy and
Sort options, like Issue Note Lists.

handle paginated results that are only one page

* Update event_types.go

* Update event_types.go

After having another look, this seemed more consistent with other method
names used in this package.

* fix godoc for RepositoriesService.RawFileContent

* rename RepositoriesService.RawFileContent to RepositoriesService.GetBlob

* add public_jobs setting to CreateProject

* fix json field name

* rename PublicJobs to PublicBuilds

* Fix #516.

* Order the fields of GroupMember to match the GitLab docs.

Signed-off-by: Sune Keller <absukl@almbrand.dk>

* Add ParseWebhook function to automatically parse events from webhook requests

* Add tests

* Use constants over strings for webhook struct types

* Re-export WebhookEventType method; add test

* add HEAD get file metadata

* add new endpoint HEAD GetFileMetaData

* add user status endpoints

* fix doc links

* fix style and a mistake

* Support push rules for projects
 (#501)

* fixed AuthorEmailRegex (must be string instead of bool)

* rename variable ph to ppr (ProjectPushRule)

* implement review comments

Fixes #505

It seems some fields were outdated/wrong. Fixes #502

* Addling support for license api endpoint

* Fixing time fields to proper structs

* license.go: giving date fields proper struct type

* license.go: moving 'license' string literal to NewRequest call

* license.go: moving AddLicense function to option struct POST to fall inline with the rest of this package

Sessions is a V3-only API and should no longer be included in this
library.

* Adding missing users fields, updating docs link

* Fixing bad single quote

* runners.go: Adding IPAddress field, updated docs url

* Fixing doc link