plugins xep-0060, xep-0277: code simplification/cleaning/fix: - plugin xep-0060: moved rsm data to a more general metadata dict, which will contain all data relative to the node/items set. RSM metadata are prefixed with "rsm_" - plugin xep-0060: minor docstring fixes - plugin xep-0060: removed cache to simplify code base - fixed broken getLastMicroblogs - added _getLastMicroblogs as wrapper to getLastMicroblogs, for bridge - removed lxml dependecy for this plugin, use native twisted instead - several improvments/fixes in item2mbdata

Use this module to temporary store files that need to be integrated to other
projects such as Wokkel.

For example, the changeset that introduced this folder adds RSM (XEP-0059)
support to Wokkel. The files in sat.tmp.wokkel are imported over the initial
wokkel files from sat.plugins.__init__.py