Isolate Cinder Attach and Connect in Base Driver

The base Cinder Driver combines the Attach process and the
actual Connect process all under the Attach method.  This makes
sense, but the method can be split between the parts that perform
things like DB updates and RPC calls and those that just take iqn
info and actually make connections to the Cinder Volume Node.

This would allow Drivers to utilize the connector portion of the
code to add enhancements of their own.

Change-Id: I9e3cd24dc978e7c7672bf1eb09626428d2ba144d
Fix HNAS driver initialization

In iSCSI driver, when CHAP authentication is enabled, the driver would throw
an error message in the attempt to create the first volume after the driver
initialization. This is fixed by passing the right value to set_targetsecret.

Closes-Bug: #1402773
Change-Id: I554a67a2e19edb2e09c12febc339522719dfbe00
Merge "Isolate Cinder Attach and Connect in Base Driver"
Merge "Fix HNAS driver initialization"