Ensure the last modified timestamps are formatted correctly.

Also: move from last_modified to getlastmodified.  Dav4rack prefers the
former (with its lookup table), Meishi prefers the latter (directly
translating acceptable attributes into method names).

Signed-off-by: Alex Zepeda <alex@inferiorhumanorgans.com>
Followup to aebae4d: rename more property accessors.

Dav4rack prefers to give accessors pretty method names and use its
lookup table.  Meishi prefers directly translating acceptable attributes
into method names.  For properties covered by dav4rack and Meishi this
is entirely a stylistic change.  For CardDAV specific properties, this
is required.

Signed-off-by: Alex Zepeda <alex@inferiorhumanorgans.com>
Clean up some of the logging.