Rename object converters

There are plenty of functions that convert OpenStack objects
to dictionares to return them to user. This commit changes
names of such function to end with 'to_view', to make
them more correct (e.g. images came from glance, not from nova)
and unified.

Change-Id: Ida50e2d5dc8b145fa7df2bfd6f9637356353ea7e