Fixed a whole bunch of documentation issues

You'll still need to go through and describe a bunch of @param variables @Simongoring. But for now, check_doc() passes cleanly.
Addressed a few issues in #141 especially item 2.
Minor enhancements to the README
Updated the devtools code. Library over require and new devtools syntax
Fixing conflict for `compile_list` to address @gavinsimpson's comment in the doc_fix branch.  Wil llink to commit when it's done.

Merge branch 'doc_fix' of http://github.com/ropensci/neotoma

Conflicts:
	R/compile_list.R
	R/compile_taxa.R
	R/get_contacts.R
	R/get_dataset.R
	R/get_datasets.R
	R/get_download.R
	R/get_geochron.R
	R/get_site.R
Merge pull request #144 from SimonGoring/master

Accepted changes to `README`, are my changes to `compile_list` what you expected?