more helpful error message on failure

on HTTP failure the corresponding exceptions from
pycarddav.carddav.requests.exceptions are now raised via
response.raise_for_status()

fixes github #33
changed vagrant test
more helpful error message on failure

on HTTP failure the corresponding exceptions from
pycarddav.carddav.requests.exceptions are now raised via
response.raise_for_status()

fixes github #33
Merge branch 'vagrant' into develop
Merge branch 'master' into develop
netrc should not be required anymore

but should still work, needs further testing.
Also there is no documentation on the netrc files.
updated todo file (should be deleted anyway)
Support for "text/x-vcard; charset=utf-8" as a value for getcontenttype
Do not fail if FN is empty
Updated the configuration handling.

The Configuration Parser now relies on a collection of Section
Parsers. The Configuration Parser reads the file sections one at a
time, using the matching section parser. The produced data sets are a
wrapped in a Namespace, and can be unique or belong to a collection.
The Configuration Parser returns all those data sets in a top-level
Namespace. The data read on the command line is also stored in this
top-level Namespace. Its content depends on the tool used.

pycardsyncer is broken at the moment, since it is not aware of the new
WebDAV accounts configuration.
More configuration handling updates.

Configuration checking is now split into check, check_accounts and
check_property. All the default parameters are checked in the root
Configuration object.

More exceptions are catched during parsing. Useless check of
sqlite.path is removed (since a default value is provided if missing).
Modified the syncer for the updated configuration.

For now, it only considers the first defined account.
Added a parameter to bypass the accounts checking.

This is specially useful for tools working only on the database (like
pc_query) which thus never ask for a webdav password.
Cosmetic change on configuration dump.
Added the --account option on pycardsyncer.
Merge remote-tracking branch 'agateau/accept-empty-fn' into develop
Merge remote-tracking branch 'agateau/charset-utf8' into develop
Merge remote-tracking branch 'dsoulayrol/conf_update' into multi_account
Merge branch 'develop' of github.com:geier/pycarddav into develop
Support for "text/x-vcard; charset=utf-8" as a value for getcontenttype