Fix nfs_shares config file parsing of spaces

Driver fails in case if 'nfs_shares' file lines contain more than one
space between it's patrs. This patch fixes this.

Change-Id: I446ab23f0ae06ec9e8ad18ebc1d79c705de47e4d
Add genconfig tox job for sample config file generation

Wrap generate_sample.sh in tox. This will make sure needed
dependencies are installed prior to sample config file generation.

Change-Id: I426be3416931a385f99ca5270943a0f10c60f346
Remove global conf settings from iscsi helper

This "intermediate" iscsi helper pulls all of it's
config settings from the global config.  This is fine
if you only have a single backend, but if you do
multi-backend it puts things in a bad state where some
of the backend specific settings are picked up but
others are not (for example iscsi_ip_address).

This change modifies methods like create_export in
the volume/iscsi helper to take the drivers version
of the config settings as a parameter and use those
instead of setting off of the global values.

Long term there's a lot of cleanup surrounding our
inheritance model and especially the iscsi helpers.
We can address that going forward but here we just want
to fix the bug in the safest way possible.

Change-Id: If17ec3ffb3f4ea7f95da65781885dcd613b1a807
Closes-Bug: 1325799
Merge "Fix nfs_shares config file parsing of spaces"
Merge "Remove global conf settings from iscsi helper"
Merge "Add genconfig tox job for sample config file generation"