Reverting the hostcaching option to default value
Fix vm docker create invalid flags

The commander module doesn't allow short flags longer than one letter

Fixes these issues:
https://github.com/MSOpenTech/azure-sdk-tools-xplat/issues/16
https://github.com/MSOpenTech/azure-sdk-tools-xplat/issues/17
Commands for managing static IP addresses

Added commands:
azure vm static-ip show <vm-name>
azure vm static-ip set <vm-name> <ip-address>
azure vm static-ip remove <vm-name>
azure network vnet static-ip check <vnet> <ip-address>

Added --static-ip option to:
azure vm create
azure vm docker create