validate flat networks physical name

Modified flat driver to validate the physical network
name - we make sure that empty names are deducted.

unit test changes:
- added two tests to make sure that we detect empty
  physnet names
- fix bug in existing unit-tests
-- flat_networks should be a list of string and not string
- use conf to setup flat_network

Change-Id: Ib7cfbd3c97d2e95c82044a2cba683c917ea54a84
Partial-bug: #1325664
Updated from global requirements

Change-Id: I4e105ae586e8a2379f3025f6f0d0344738b4e925
BSN: Remove db lock and add missing contexts

Adds context tracking decorators that were missing
from router interface methods. Without them, new
sessions were being created instead of using the
existing context which was causing transaction
issues.

Modifies the servermanager to store context references
as weakrefs so if multiple functions are called before
the rest functions are called, the first one doesn't steal
the only context reference with a pop() call.

Removes a DB lock for update in the server manager that occured
during rest calls that was triggering deadlocks due to the
file lock synchronization for the rest calls.

Closes-Bug: #1336251
Change-Id: Iad3d61e2c23832b3ad760a999fbab7feaa13f805
NSX: fix indentations

Commit f43eb49f56accab87e4d1b6defcf78d1e697f9e6 had invalid
indentations.

Change-Id: I795d1960e79cc6fae889fbe8fca264d9e60e6f08
Merge "BSN: Remove db lock and add missing contexts"
Merge "validate flat networks physical name"
Merge "Updated from global requirements"
Ignore variable column widths in ovsdb functional tests

The ovsdb tests check the output of "ovsdb-client monitor" before and after
some operations. The first line of output is a header row with spaces for
column separation. The column widths can vary depending on the data in the
columns, so compress multiple spaces to one for testing.

Change-Id: I6b4690ea9ef1c1b215411ca2c39b1e65fec2c6c7
Partial-bug: #1336172
Merge "NSX: fix indentations"
Merge "Ignore variable column widths in ovsdb functional tests"