Use correct URI for DELETE requests.

We cannot use incidence.customProperty("buteo", "uri") since the storage
backend removes all custom properties from deleted incidences. We also
cannot use its UID as there is, in general, no correlation between the
UID of an incidence and its URI on the server.
However, we only DELETE an incidence if it is still on the server, and
all locally deleted incidences which are still on the server are
downloaded by fetchRemoteChanges. Therefore we can determine the URI by
searching mReceivedCalendarResources for the deleted incidence.
Do not use Reader::hrefToUid to determine the UID of an incidence

For some servers (e.g. Owncloud), the uid of an incidence cannot be
derived from its uri. As a consequence, remote incidences are not
correctly mapped to local incidences when Reader::hrefToUid is used.
Merge pull request #34 from sdrave/remove_hrefToUid

Do not use Reader::hrefToUid to determine the UID of an incidence
Merge pull request #35 from sdrave/fix_delete

Use correct URI for DELETE requests.
Bump version
[buteo-sync-pluging caldav] Own Owncloud improvements.

Following commits missed proper changelog format:
- Do not use Reader::hrefToUid to determine the UID of an incidence.
- Use correct URI for DELETE requests.
- Fix ICal data encoding to match the Content-Type header.
- Let Reader class parse all retrieved iCalData.
- Refactor Report class, move processing of ETags to NotebookSyncAgent.