The previous location was /usr/etc/syncevolution. It should have been
/etc/syncevolution in our debs, with proper declaration as system
config files. The intention was that system admins can add or modify
templates.

Not particularly likely, so now template files are only searched in
/usr/share/syncevolution/templates (or whatever was chosen with
configure --datadir).

Also added a README to that directory, warning that copying these
files will lead to incomplete configs. Each main config.ini carries
a similar comment, for those who miss the README.

Part of the D-Bus API testing is checking of the GetConfigs()
call for templates. So when adding a new server template, that
test must also be updated.

The server config.ini files and icon.[svg|png] in src/default will be installed
in /etc/default/syncevolution. All configurations found there extend and/or
override the builtin templates. The advantage is that file-based templates
can have icons and that templates can be added/modified without recompiling
SyncEvolution.

This meta information is now part of EvolutionSyncConfig:
- getWebURL() returns a URL with further information; this
  replaces the hard-coded URL string that was previously
  returned as comment for templates in the ServerList
- getIconURI() currently returns absolute file paths to
  an icon file (example: icon.png for ScheduleWorld). The
  content and exact URI may vary, depending on how system
  administrators or distributions configure SyncEvolution.
  If possible, callers should be able to handle http://
  and other URI access methods.