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"
}

* Support for AcceptMergeRequest parameters

* Fixup PR #82

* PipelineEvent type changed

* Added BuildEvent

* fixing typo

* Refactoring with existing struct type

* Fixed different type object form

* fixing auto generated interface types to string

* Added PushEvent, MergeRequestEvent, PipelineEvent, BuildEvent unmarshal test

* Added GroupMergeEvent type

* Remove GroupMergeEvent and fix MergeEvent for Group Webhooks

* Add Milestone.StartDate to Issue

* Use Milestone struct

* Use pointer for Milestone

* add EMail endpoints from gitlab api

* added changes requested

- gitlab.CreateProjectOptions.ContainerRegistryEnabled
- gitlab.Project.OnlyAllowMergeIfBuildSucceeds
- gitlab.Project.LFSEnabled
- gitlab.Project.RequestAccessEnabled
- gitlab.Project.ContainerRegistryEnabled

* add parameters “since” and “until”

* update API Docs URL

* closes #77 - adds `web_url` field to `Issue`

* Add new fields in Issue struct to bring it up-to-date with Gitlab API

The following fields have been added to `Issue` struct
* `Subscribed`
* `UserNotesCount`
* `Confidential`
* `DueDate`
* `WebURL`

Add ops is equal to null judgment

https://gitlab.com/gitlab-org/gitlab-ce/issues/21468

Tags is now a separate service, following the Gitlab API structure.

* Add support for /projects/*/builds/*
PR for issue #42

* fix

* modify comments

* modify comments

* change styles and perform some addtion/deletion according to comments

* define Runner as a independent type

* define ArtifactsFile as a independent type

* remove type Runner and ArtifactsFile, and remove field Coverage