Make PUT consistent for `_mapping`, `_alias` and `_warmer`

This pull request makes consistent the PUT for `_mapping`, `_alias` and `_warmer` as described in issue #4071.

### `_mapping`: 

Single type can now be added with

`[PUT|POST] {index|_all|*|regex|blank}/[_mapping|_mappings]/type`

and

`[PUT|POST] {index|_all|*|regex|blank}/type/[_mapping|_mappings]`

### `_warmer`

A single warmer can now be put with

`[PUT|POST] {index|_all|*|prefix*|blank}/{type|_all|*|prefix*|blank}/[_warmer|_warmers]/warmer_name`

### `_alias`

A single alias can now be PUT with

`[PUT|POST] {index|_all|*|prefix*|blank}/[_alias|_aliases]/alias`