Pbiering testing

[pbiering]

splitted now:

• partial from pbiering-testing #568

More coming afterwards

=== below historic information ===

Superseeds/includes my older pull requests

• filter broken vcard entries before delivered, found on real life syst… #519
• improved request logging #518
• try/catch of objects avoiding not serving any object in case an object has no valid contents #517

and includes also other (merged) pull requests:

• Cleanup/Improve storage.py #512
• <report> should contain XML elements, not text #521
• remove umask(0) in daemon mode #540

and includes:

• Items/Props caching (speed up a lot, one sync request with WP results already in approx. 80% hit), cache statistics are logged after every request or after minimum interval on info level
• request/response logging only if 'debug' option is explicitly given
• add example config for dedicated debug log
• additional debug_filter option to disable some debug logs conditionally
• catch broken items during PUT before storage to filesystem to avoid empty files

it's strongly recommend to use this in combination with

• python-vobjects 0.9.3 + encoding bugfix honor empty ENCODING and not empty CHARSET for decode/encode and fix base64 encoding skarim/vobject#49

Until implemented do not offer "sync-collection" (and "sync-token"), see also

• Support for sync-collection REPORT #306

[pbiering]

rebased with current master, try to split in several smaller pull requests now

[Unrud]

I'm closing this:

• A separate tool for checking the storage is unnecessary, because error message now contain the paths of invalid files.
• The memory cache is superseded by the on-disk cache.
• The logging filter is too complicated. The non-debugging log output is now less verbose and should contain everything that is required for identifying the cause of problems.
• The various small improvements to log messages got handled by a general overhaul of all log message.
• The examples for log file rotation are included in the documentation.