UX improvements for Launch Instance dialog

This patch solves two UX issues on the Networking tab
of Launch Instance dialog:

1) "nic" is lowercase when the acronyms usually are capitalized.
2) "Selected Networks" and "Available networks" do not follow
the same capitalization convention.

Change-Id: If83f605dc2ebbfd408811634da2bad231356f057
Closes-Bug: #1325684
Merge "UX improvements for Launch Instance dialog"