bump pandas to 0.12
simplify join code
change io to readers to avoid namespace conflict
check for empty list of groups
use drop over del, remove_bamboo_reserved_keys returns dframe after drop
declass some of core frame, fix type issue
remove conversion methods from bframe class
pull out reco dates and join ds
remove BambooFrame
remove deprecated example
fix var collision, dframe encode loc
cleanup observations
update stats first to avoid inplace encoding issue
wrap json load in df
faster schema col drop
cleanup readers
clearer exception fall
spacing tweaks
messaging tweak
cleanup calculator syntax