Update README.markdown

Replaced gendered terms/pronouns.

This is a great project, and it can be even greater if it doesn't perpetuate the assumption-of-maleness that seems to pervade all tech spaces.

I do realize that "a man's home is his castle" is a saying, and not just arbitrary, but I counter that with the age old argument: But Still.
Merge pull request #64 from zacharyalexstern/master

Update README.markdown to remove gendered terms