based on docs https://docs.gitlab.com/ee/api/packages.html and inspired by GroupProjectsFilter

- readme_url
- can_create_merge_request_in
- import_status
- ci_default_git_depth
- remove_source_branch_after_merge
- auto_devops_enabled
- auto_devops_deploy_strategy
- auto_devops_enabled
- statistics.packages_size
- shared_with_groups.group_full_path

fix #613 #632 #667

Added option to preserve underscores in the JacksonJsonEnumHelper to fix TargetType.MERGE_REQUEST value. (#615)

* Added Encoding constant (#342).
* Mods to use Encoding enum constant (#342).
* Mods to support reading content from files when using CommitsApi.createCommit() (#342).

* Added support to list MergeRequests by state
* Added getMergeRequests by State with paging support

* [Add]Add gitlab project milestone api.

* [Add]Check projectId not null.

* [Fix]Fix some bugs.

* [Add]Add gitlab issue notes api.

* [Add]Add gitlab labels api.

* [Imp]Add attr-required to Param.

* [Fix]Fix test error.