Merge pull request #90 from shaitan/master

json statistics: added vfs and device statistics. Updated documentation.
v0.22.2
Merge branch 'master' of github.com:reverbrain/eblob
json stat: added link to kernel.org documentation
stat: do not cache statistics in static buffer, it is not thread-safe other backend request can overwrite this data under us
v0.22.3
stat: added malloc() return value check
stat: fixed null-byte json string generation
v0.22.4
json_stat:
  * do not fail all stat if some stats are not available.
  * fixed gcc warnings with fscanf.