Remove nvplib and move utility methods into nsxlib

This patch completes the process of moving code from nvplib
to nsxlib. Utility methods such as do_request and get_all_query_pages
are transferred into nsxlib, so that nvplib can be safely removed.

Partially implements blueprint nicira-plugin-renaming

Change-Id: I43be18c89ac908ebae32b39a8508a7006b5fe328
Merge "Remove nvplib and move utility methods into nsxlib"