duplicated functionality for slack_history

[yonicd]

there was already a function for this in the package.

https://github.com/hrbrmstr/slackr/blob/master/R/history_slackr.R

most of the piping for other functions is already builtin for the one i added

[raybuhr]

I'm willing to retract/deprecate the history function I submitted and forward any calls to it to your new version. I would like to add the search by date range feature my history function adds, if that's cool with you, though.

[yonicd]

that's fine. thanks

[yonicd]

btw that option is there already

[raybuhr]

PR #65 deprecates the slackr_channel_history function in favor of history_slackr

[yonicd]

merged https://github.com/hrbrmstr/slackr/pull/65