* Add Build Trigger endpoints

* Update variable name

* Add a WithContext function, Fixes #143

This enables the use of requests with a specific context attached.

* Fix indentation

* Add a test

Fixes #145.

This adds the `can_push` option to the AddDeployKeyOption and DeployKey structs, in line with what is supported by GitLab.

* Add statistics information and flag to query options

* groups do not expose a CommitCount

* make the sizes unsigned, negative values dont make sense

* repair tests

* add review comments

* remove wrong tagging from field

* Adds support for creating commits

* Adds support for cherry-pick commits.

* Fixed indentation

Add missing fields

This also renames the Go field, which may break things. Probably not a
lot though - ParentIds never had any content.

This typo probably is a result from invalid Gitlab API documentation
on tags, which also wrongly uses `parents_ids`.

I created a merge request there as well:

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9550

It looks like these options functions are pretty much always called `With…` which makes them better recognizable. So I renamed the `SudoUser` func as well as the `SudoFunc` type to make them more generic and idiomatic.

https://docs.gitlab.com/ce/api/README.html#sudo

Updated:
- GetMergeRequest
- GetMergeRequestChanges
- UpdateMergeRequest
- AcceptMergeRequest

* Correctly parse/unmarshal validation errors returned from the API

* Refactor/fix error handling

* Added support for notification settings API

* Refactor the notification settings API

* add support for paging to ListGroupMembers

* making the ListGroupMembersOptions explicit

Adds only_allow_merge_if_all_discussions_are_resolved and approvals_before_merge fields to Project and EditProjectOptions structs (#111)

* Add parameter Simple to ListProjectsOptions struct

Enables you to query list of projects with minimal
information much faster.

ListProjectsOptions{
  Simple *bool url:"simple,omitempty" json:"simple,omitempty"
}

Fields returned:
ID, HTTPURLToRepo, WebURL, Name, NameWithNameSpace, Path
PathWithNamesPace

* Add parameter Visibility to ListProjectOptions

Limit by visibility public, internal or private

ListProjectOptions{
  Visibility *string url:"visibility:omitempty" json:"visibility,omitempty"
}