OrgUnitSelector: Fix fallback logic:

Build intersection of current admin units' org units and
user's org units. If some of the user's org units are in the
current admin unit, use the first of those as the fallback.

Otherwise we're in an inter-admin unit operation, default to
current admin unit's first org unit.

(cherry picked from commit c1185313bb32af83e3b36d7ad4d1a18fea4384ef)
Refactoring: Use `key in dict` instead of `dict.has_key(key)`

(cherry picked from commit 45fccab21181ddb07f3c80c0b2d5b5bce01954db)
OrgUnitSelectors: Use OrderedDict to store units in order to

get a deterministic fallback behavior.

(cherry picked from commit fa6814fd0263dc1674e008346868f51c46d70fd8)
CookieStorage: Extend max age of cookies to 30 days (was

"end of browser session" before).

(cherry picked from commit cdf150fd123f08cda5122a04073eac664b68fd35)
OrgUnitSelector: Store selected OrgUnit after determining fallback.

(cherry picked from commit 70b680a9bb923ebb9dc907bb80669290a097a086)
Merge pull request #718 from 4teamwork/lg-backport-pr-716-to-4.0-stable

Backport "OU selector: Fix fallback logic" to 4.0-stable