Hbase Credentials implementation to store in jobConf
The jobConf is used further to pass credentials to the tasks while running
Oozie server should be configured to use this Credentials class by including it via property 'oozie.credentials.credentialclasses'
This is the interface for all the Credentials implementation. Any new credential implementaion must implement
this function. This function should modify the jobconf which will be used further to pass the credentials to the
tasks while running it. Credentials properties and context is also provided by that user can get all the
necessary configuration.