fix for move to reshape2, also drop plyr
fixup a couple of things that got munged in recent merge
missed one change that got munged
fixup to account for move to reshape2
fixup to account for move to reshape2, plus some bug fixes. Needs work...
update documentation
Forgot to add the data files to the Collate list.

Added taxon.table.R and translate.table.R to the Collate list in
DESCRIPTION.
fixed "returns", changed metadata in get_download

get_download returns only one object ever (unless we make it do multiple
calls to the API), so it can have a unique message, that now indicates
which site was returned, to act as a check for the user.

Also, \code{site.data}, \code{pi.data} and \code{meta.data} are all
metadata, so I've moved them into a list object.  I'm keeping
\code{sample.meta} out for now because it relates directly to the actual
sample data.
Merge pull request #36 from SimonGoring/master

get_download, returns better message, meaningful metadata.