HPE Nimble storage driver

[fideltak]

What this PR does / why we need it:
Adding HPE nimble storage driver.

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #
N/A

Special notes for your reviewer:
This is initial req for nimble driver.

Release note:

This driver has below functions for now.
- Create volumes.
- Delete volumes.
- Create snapshots.
- Delete snapshots.
- Extend volumes.
- Attach volumes.

[xing-yang]

Thanks @fideltak for submitting the HPE Nimble driver! We'll take a look.

[wisererik]

Hi @fideltak, thanks you for developing Nimble driver. there are some suggestions for your code:

1. Use goimport tool format go code, some go ides will help you format code, such as golite, goland.
2. Un-used code should be removed.
3. For error log message, please use lowercase.
4. Add license description in the header of *.go file, like the following:

// Copyright 2019 The OpenSDS Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

[wisererik]

1. it seems that missing initialisation and clean part in contrib/drivers/drivers.go->Init and Clean
2. please fix CI error

[leonwanghui]

@fideltak Please resolve the ci conflict error.

[coveralls]

Coverage decreased (-0.008%) to 28.363% when pulling 1b7f4df on fideltak:nimble into 7c9ba74 on opensds:development.

[leonwanghui]

Could u use make goimports command to format the code style?

[leonwanghui]

Generally it's LGTM, please update your code

[kumarashit]

Overall LGTM..
Thanks

[wisererik]

LGTM

[leonwanghui]

LGTM