Reload logger config on SIGHUP

Particularly useful for logrotate.
Return user basepath for current-user-principal

Fix #196

The way to do collection discovery described in
http://stackoverflow.com/a/11673483 doesn't work well with Radicale:

1. current-user-principal returns /user/calendar.ics/

2. PROPFINDs asking for calendar-home-set will return the URL that was
   used in the request, which is still /user/calendar.ics/

3. The final PROPFIND with Depth: 1 is supposed to list all collections,
   but because the request is done with a collection URL, Radicale returns
   the items for the "calendar.ics" collection which might or might not
   exist.
Remove props file when deleting a collection with multifilesystem
Merge pull request #198 from untitaker/discovery

Return user basepath for current-user-principal
decode http resquest content later
Merge pull request #224 from deronnax/decode_content_later

decode http resquest content later
add ".well-known" addresses feature (closes #126)
now with regex
throw 401 in case of failed variable substition for .well-known url
Merge pull request #225 from deronnax/well-known

Support "well known" URLs
Cosmetic changes
Don't recreate the regular expression for each request
Merge pull request #211 from vuntz/delete-multifilesystem

Remove props file when deleting a collection with multifilesystem
Merge pull request #191 from bouttier/reload-logger-config

Reload logger config on SIGHUP
Comment all out in sample config (fix #155)
Merge branch 'master' of github.com:Kozea/radicale
Fix Python 3 compatibility
Update NEWS
Don't crash because of missing SIGHUP on Windows

Fix #229.
Forget Python 3.1 in tox.ini