Replace .onLoad() with .onAttach() per #33
Remove the word "Warning" from a printered error message so that the package can pass a CRAN check that appears to search for the word at install.
Replace the writeLines(strwrap(x)) idiom with the packageStartupMessage(x) idiom.
Use .onAttach() only to provide the user the repo url, and use .onLoad() to check that the retriever is on the path per #35
Merge pull request #35 from dmcglinn/startup

Improve the behavior of the package when attached