changed session timeout according to https://github.com/globaleaks/GlobaLeaks/issues/510
fix against https://github.com/globaleaks/GlobaLeaks/issues/498
fix against https://github.com/globaleaks/GlobaLeaks/issues/483
aligned an UT in test_authentication.py to latest implemementation
implemented fields validation fixes https://github.com/globaleaks/GlobaLeaks/issues/518
removed a test reintroduced by an erroneous merge
added possibility to resfresh session by doing a GET on the /authentication API
fixed an error on authentication UT (on logout) now spotted thanks to previous commit
addressed issue https://github.com/globaleaks/GlobaLeaks/issues/300
removed decoy traffic handler and related staff (completely moved to tor2web)
updated tip status page with context info: https://github.com/globaleaks/GlobaLeaks/issues/513
extended fields with preview key for https://github.com/globaleaks/GlobaLeaks/issues/515
updated tip list with preview (handler and test) https://github.com/globaleaks/GlobaLeaks/issues/515
Merge pull request #149 from globaleaks/issue/513

Issue/513
Merge pull request #148 from globaleaks/issue/515

Issue/515
UT aligned to fix to issue 513
moved supported_extensions in GLSetting
Merge branch 'master' into issue/300
Merge pull request #147 from globaleaks/issue/300

addressed issue https://github.com/globaleaks/GlobaLeaks/issues/300
Merge branch 'master' into issues/112

Conflicts:
	globaleaks/handlers/authentication.py
	globaleaks/tests/handlers/test_authentication.py