move NetworkUtils to WPUtils subtree
fix an issue while in airplane mode, progress bar was never stopping
add a network mode in PullToRefreshHeaderTransformer to show a different message when network is disabled
remove unused code
set network refresh mode as default
use the PTR library version 0.9.7
disable refresh on the attacher
Merge pull request #1786 from wordpress-mobile/issue/1568-change-ptr-message-no-connection

fix #1568 change ptr message no connection