backend: replace Pylons with TurboGears2 Replace the no-longer-supported Pylons application framework by TurboGears2 which is largely compatible/similar to Pylons. Some interesting history is described at: https://en.wikipedia.org/wiki/TurboGears Changes by Dominik Ruf: - fix sql config in test.ini Changes by Thomas De Schampheleire: - set-up of test suite - tests: 'fix' repo archival test failure Between Pylons and TurboGears2, there seems to be a small difference in the headers sent for repository archive files, related to character encoding. It is assumed that this difference is not important, and that the test should just align with reality. - remove need to import helpers/app_globals in lib TurboGears2 by default expects helpers and app_globals to be available in lib. For this reason kallithea/lib/__init__.py was originally changed to include those files. However, this triggered several types of circular import problems. If module A imported something from lib (e.g. lib.annotate), and lib.helpers imported (possibly indirectly) module A, then there was a circular import. Fix this by overruling the relevant method of tg AppConfig, which is also hinted in the TurboGears2 code. Hereby, the include of something from lib does not automatically import helpers, greatly reducing the chances of circular import problems. - make sure HTTP error '400' uses the custom error pages TurboGears2 does not by default handle HTTP status code '400 (Bad Request)' via the custom error page handling, causing a standard non-styled error page. - disable transaction manager Kallithea currently handles its own transactions and does not need the TurboGears2 transaction manager. However, TurboGears2 tries to enable it by default and fails, throwing an error during application initialization. The error itself seemed to be harmless for normal application functioning, but was nevertheless confusing. - add backlash as required dependency: backlash is meant as the WebError replacement in TurboGears2 (originally WebError is part of Pylons). When debug==true, it provides an interactive debugger in the browser. When debug==false, backlash is necessary to show backtraces on the console. - misc fixes

--- a/development.ini	Sun Jan 15 20:57:47 2017 +0100
+++ b/development.ini	Sun Jan 29 21:08:49 2017 +0100
@@ -512,7 +512,7 @@
 ################################
 
 [loggers]
-keys = root, routes, kallithea, sqlalchemy, gearbox, beaker, templates, whoosh_indexer
+keys = root, routes, kallithea, sqlalchemy, tg, gearbox, beaker, templates, whoosh_indexer
 
 [handlers]
 keys = console, console_sql
@@ -553,6 +553,12 @@
 qualname = kallithea
 propagate = 1
 
+[logger_tg]
+level = DEBUG
+handlers =
+qualname = tg
+propagate = 1
+
 [logger_gearbox]
 level = DEBUG
 handlers =