Merge branch 'release/0.3.1' into develop
change zookeeper directory structure: fixes #51

* each actors register itself into /jubatus/actors/<type>/<name>/nodes/
* each keeper register itself into /jubatus/jubakeepers/<type>/
* jubactl looks up those directories above with -t <type> option
* fix generator to generate proper <type>_impl.cpp and <type>_keeper.cpp
refactor keeper a bit
Fix get_status PROGNAME to return real program name: fixes #79
fixes issue #81 jenerated *_impl.cpp and *_keeper.cpp are invalid.
fix #82 jenerator -o option
fix #83 omake regenerate says failed in spite of success
Support jubatus server options in jubactl/jubavisor: fixes #75
jenerator was not wrong...
add #@nolock directive to the jenerator and a bit refactor, separate files
solving #77 by using unsave #@nolock directive to avoid deadlock
get_loads implemented
merged 49528214
keeper should return status
add problem discription
make waf use GNU-compatible command line options
lexer and parser almost written
memoized samples
remove jubatus.pc installation as pkgconfig files are automatically copied by waf
update waf to 1.6.4 to workaround the problem that waf installs pkg-config metadata into wrong path