New unit tests setup for bkr.server.

Change-Id: I5afe71f4b10e5831202dab5ed5189cd8a77a27fe
Initial TaskLibrary unit tests.

Bug: 965915
Change-Id: I7938bcdbac2fe875bcc5e87082893d002d5621c7
tests: merge test_system_take and test_system_available

There was a lot of overlap in the cases covered by these two test
modules. As an added bonus, test_system_available is converted to
WebDriver (almost) for free.

Change-Id: Ie61dc1eb5f9e8fabaed99a58c3c83b92249c493d
access policies: data model

Change-Id: I61e4befd63d763afcd95f90e4588341408555bcc
access policies: remove Shared and group admin privileges

Change-Id: Ieecd68ee57bab5fcfaf08e2d1da9b47cb8abd468
access policies: user interface

Change-Id: Ic2ae462ef4af5112d21d9754da150680470dea90
access policies: use Twitter typeahead.js for groups and users

Change-Id: I95583da88aa60c255d4c41378b56a6c857c26f21
access policies: docs and release note

Change-Id: Ie9d62c98c019eba1f3e60fffa7ba86c51d40d9fc
access policies: enforce control_system permission

Change-Id: I3a29011061a6de67da98e5e37b888e146c13192c
access policies: obey loan_self permission

Change-Id: Iff14ef6a62b4e0f91da3f97fc91a2056772c49d5
Merge changes Iff14ef6a,I3a290110,Ie9d62c98,I95583da8,Ic2ae462e,Ieecd68ee,I61e4befd,Ie61dc1eb into develop

* changes:
  access policies: obey loan_self permission
  access policies: enforce control_system permission
  access policies: docs and release note
  access policies: use Twitter typeahead.js for groups and users
  access policies: user interface
  access policies: remove Shared and group admin privileges
  access policies: data model
  tests: merge test_system_take and test_system_available
Merge changes I7938bcdb,I5afe71f4 into develop

* changes:
  Initial TaskLibrary unit tests.
  New unit tests setup for bkr.server.