Command line data-collection tool

Trond, Matt suggested that you'd be the best person for this since you're already working on each of our supported platforms.

The idea is to have a command line tool that can be invoked by the user even if ns_server is down that will produce an archive file containing all the needed information. In addition, if the user goes to /diag when ns_server is up, it will execute this same tool on each node, packaging up the individual archives into a single archive that the browser will then download.

For portability, the tool should be invokable by ns_server using the same relative pathname on each platform, the same way memcached, moxi, and vbucketmigrator are right now. It should either take a filename as an argument or just write a file to a standard temporary directory and give the filename as output in a way that's easily parseable with the same Erlang code on all platforms.

The list of things support (Perry) would like to see collected is at http://hub.northscale.com/wiki/index.php?title=Support_Tools . We should implement the low-hanging fruit first, with at a bare minimum the browse_logs output being included.

I will be happy to write escript code to grab any data that's needed from Erlang when ns_server won't start.