syntax fixes

[jiata]

consolidated syntax:

• strings use the "{}".format(...) style
• '' is used as the default (as opposed to "")
• _variable_name >> variable_name

cleaned up print lines from commands

made command params more simple:

• "--cluster-id" >> "--id"
• "--cluster-vm-size" >> "--vm-size"
• ./bin/spark-cluster-get --cluster-id my-cluster >> ./bin/spark-cluster-get my-cluster

[msftclas]

@jiata,
Thanks for your contribution as a Microsoft full-time employee or intern. You do not need to sign a CLA.
Thanks,
Microsoft Pull Request Bot