Refactor new win_ntp module

Use built in service management functions to handle starting/restarting
services.
Fix windows service.restart

Instead of doing weird sleep/recheck stuff, just use the existing
stop/start functions.
Make sure that state.sls/state.highstate cache files are not read-only

This fixes an error that occurs on Windows minions where default
permissions are inherited and files are created initially as read-only.
Fix windows service.status

Just looking for "PENDING" and considering the status as running is not
correct, because there is a STOP_PENDING and a START_PENDING.

Also fixed a possible race condition in stopping/starting a service,
where the service could still be in STOP_PENDING when salt attempts to
start it.
Add get_pending_computer_name function
Add new windows states to the docs
Add win_system state module
Alias get_computer_description to get_computer_desc
Add win_ntp module to docs
Fix system.set_computer_desc

This would always return that the description had been changed,
resulting in the corresponding state always thinking the change had been
successful. This commit fixes that behavior.
Alias set_computer_description to set_computer_desc
Suppress function aliases from appearing in docs
Remove inapplicable exclude-members directive
Add versionadded directives to new modules/states
Merge pull request #7720 from terminalmage/windows-net-states

Add win_system state, refine win_ntp module