fix PyPI description links

simplify node cache and acd client

Introduced collective classes NodeCache and ACDClient composed of mix-ins.

misc:
 - faster folder insertion
 - fixed node purging (closes yadayada#28)
 - plugin mechanism changed
 - fixed nlink calculation for folders

FUSE fixes, add FUSE xattrs

Fixed invalid file chunk range requests with offset == file length.
Fixed rename (overwrite) for files that have a name doppelganger
in the trash.

Added some node info as extended attributes (xattrs).

misc:
- added write timeout to WriteStream to avoid certain
  locking behavior
- increased node attr (validity) timeout
- enabled multi-threaded FUSE by default
  (added single-threaded mount argument)
- add nonempty mount argument

fix move action, add cat action

Move action was still broken (really fixes yadayada#62). Now, old parent ID
is necessary (API restriction) and parent count must be 1 (restriction
arises by method of node resolution).

Added cat action to stream files to stout.

Minor changes:
- OAuth procedure now asks for keypress before opening browser
- query.get_root_node fixed
- added startup check for empty node cache (yadayada#105)
- added startup python version check (yadayada#104)
- 0.1.3 cache migration removed

close StreamChunks on file release

Added release method for StreamedResponseCache for closing
unnecessary file chunks. Should prevent excessive number of open
sockets (concerns yadayada#98).

add FUSE other/root access, dedup fix

- added access options for FUSE mount: allow_root, allow_other
- api.content: correct dedup check parameters for duplicates

bug fixes

- number of links added to FUSE getattr
- deduplication also for non-existing files
- dedup mode formatter fix
- setup.py: read in utf mode (concerns yadayada#64)
- added --utf argument to force utf-8 output

add FUSE read support

This greatly improves FUSE read speeds by streaming chunks on read operations
compared to experimental FUSE release. Reduces read timeout to 5 seconds.
Moving and renaming should now work.

misc:
- raise RequestError on incomplete download (yadayada#57)
- moving nodes now done using add-child and remove-child (fixes yadayada#62)
- cache.query: new resolve method tha returns (node, parent) tuple

beta bump

- node cache sped up by using raw SQL for file insertion and bulk deletion (closes yadayada#50)
- node listing formats compacted
- cache queries "list_children" and "tree" are now generators
- cache.format module created from Formatter classes in cache.query
- optional coloring for node listings via --color | -c [always|auto|never]

- cache init now performs integrity check
- dump table sql method added

- re-added local oauth method for privacy concerned users
- synced writing of oauth data

misc:
- lots of unittests added
- broken pipe exception now caught
- version validity is now checked by setup.py

new transfer job queue

* added QueuedLoader
  - concurrent transfers (yadayada#7)
  - retry on error (disabled by default)
* retry_on decorator added for transfer functions (jobs)
* api: add multiple read/write callbacks api for ul/dl
* api: progress printing removed
* api: fix for resuming of incomplete downloads
* db conn thread check disabled
* single file progress wrapper FileProgress added
* progress aggregator MultiProgress added
* progress speed determination improved
* download behavior changed to skip existing files