* + ClosesIssues

* Fixed style
Add err check

* + CreatedAt

* +UpdatedAt

* + TimeStats to issue

* Change TimeStats to existed struct in issues receive

NewRequest() can potentially be called with a
nil value present in []OptionFunc. For example
this code would trigger a panic prior to this
commit:

  _, _, err := git.Users.ModifyUser(event.UserId, options, nil)

Following on to: https://github.com/xanzy/go-gitlab/pull/252

This MR exposes the SnippetsService on the client

- Centralize snippet definition in snippet.go

- Add support for description field on create, update, get for personal and project snippets

Since the response of `GET user/activities` contains a date format (`YYYY-MM-DD`) that cannot be unmarshalled into a `time.Time` automatically, additional logic was added to to cover the un-marshalling of the timestamps:

`UserActivityTime.UnmarshalJSON()`
`UserActivityTime.MarshalJSON()`
`UserActivityTime.IsSet()`

see https://stackoverflow.com/questions/25087960/json-unmarshal-time-that-isnt-in-rfc-3339-format

Thanks @lkysow for spotting these!

Target length for comments is around 80 chars.

* added _links property support in projects api

* support for _links in project api, godoc for Links struct

Project Snippets return `web_url` in the fields. Believe adding it to the struct here should allow us to pick it up.
Ref: https://docs.gitlab.com/ce/api/project_snippets.html

* add support for "Gets a member of a group or project."

* add  GroupMembersService

A user can be either an ID or a name.

And make sure we use the same struct field names as the API does.

add environments support

Add support for running pipeline triggers

typo

Add wikis api

Signed-off-by: Stany MARCEL <stanypub@gmail.com>