Log exception before converting it to a string

Also, improved error when a feed has the wrong root element.
Updated Swedish translation
GtkStatusIcon.set_blinking has been removed from GTK 3
Fix typo ("contraint")
Add spacer lines for readability in "0install show" output
Fixed exception reporting on Python 3
Added support for Tulip mainloop

Tulip is a pure-Python mainloop for Python >= 3.3. With Tulip, there is no
need for python-gobject.

Tulip is currently experimental, but as it is only used when gobject is not
present, supporting it shouldn't do any harm.
"0install add" now prints a warning if the target has a replaced-by field
Don't abort running an app if updating fails due to a read-only filesystem
Cope with read-only cache in Fetcher.download_and_import_feed

Report read-only cache errors like other download errors so that Driver doesn't
abort.
Recognise .deb files with data.tar.xz
Merge remote-tracking branch 'upstream/master'
Use new version of 0install-runenv-cli helper