Add fields for domain and path when editing a network

This will rarely be used, but may come in handy for specific
administration tasks.
Add a warning note for domain and path editing
Use existing network array for passing domain and path
Remove extra single quotes from network input keys
Prepare to update the network domain and path when necessary
Update the network with new information

We'll want to do some validation beforehand, otherwise this could
get ugly pretty quickly. For now, it works.
Update network, site, and site options with new data

This will need some better error handling and validation.
Delete the cache for the $current_site global on this network
Add wsuwp:network to the global cache groups

Otherwise things are very unpredictable.
Spacing and documentation for _update_network()
Remove the specification of meta in docs for update_network
Add basic sanitization for domain and path entries
Merge pull request #77 from washingtonstateuniversity/edit-network

[PR] Allow network URLs to be edited in the primary network admin