Add configuration items to limit secret and request sizes.

Two size attributes limit the size of secrets and requests in barbican. This CR
explicitly adds those to the Barbican configuration file.

Change-Id: I22d68cc8c9e96cf719a550b26333a845e895f178
Increase DevStack uWSGI buffer for Tempest support (Keystone Headers)

Change-Id: I597c85745f60434477886f14dd8bb7f3d5b39dd3
Merge "Increase DevStack uWSGI buffer for Tempest support (Keystone Headers)"
Merge "Add configuration items to limit secret and request sizes."