WIP: man page

A few issues I'm unclear about.

First, slightly meta: I hope I did the pull request right! This is my first one. Not sure if I should have changed 'base branch' to something other than 'master', for example.

Second: it seemed to me that the most natural place for the man page is usr/share/man/man1, so that's where I put it. But usr is in the .gitignore. I put it there anyway but the situation feels unsatisfactory to me.

Third: I and others were unable to reproduce the error Viral Shah describes in an email on [the relevant thread on the dev list](https://groups.google.com/forum/#!msg/julia-dev/ZYS2uWvePmw/2ByFeGM3nUYJ). If you have problems viewing the man page with 

`nroff -man julia.1 | less`

or a similar command, please give feedback!

Fourth and lastly: there are suggestions for possible further improvements in comments at the very top of the single file added by this commit. Feedback about whether these ideas, or others, ought to be pursued in future development would be helpful.

Please let me know any feedback you have about any of these issues, or any others.