Fix the fallout from cbc8f5cf42.

Signed-off-by: Alex Zepeda <alex@inferiorhumanorgans.com>
First pass at quota-used-bytes for address books per RFC 4331.

Signed-off-by: Alex Zepeda <alex@inferiorhumanorgans.com>
Add debugging flags in the form of environment variables.

MEISHI_DEBUG_XML_REQUEST: If >=1 log the XML request.  If >=2 pretty
print it.

MEISHI_DEBUG_XML_RESPONSE: If >=1 log the XML response.  If >=2 pretty
print it.

MEISHI_DEBUG_SUPPORTED_PROPS: If >= 1, log unsupported properties from
PROPFIND requests. If >=2, also log problems parsing the supported
properties array and the list of supported properties for a class.

Signed-off-by: Alex Zepeda <alex@inferiorhumanorgans.com>