Add validation to check whether required parameters have been obtained and are in correct format. (#77)
Add validation to check whether required parameters have been obtained and are in correct format. (#77)

* Changes:
- Add validation to check whether required parameters have been obtained.
- Check whether parameters are obtained in required format.
- Check whether specs file exists.

* Changes:
- Change exit code in case of errors.
- Use err method to print errors.
- Introduce a unique volume name parameter to create volumes with unique names.
- Handles situation when users simultaneously create volumes with same name.

umamukkara/openebs,yudaykiran/openebs