Updating installation info in manpage
Added Homebrew installation instructions
[Linux] Support the xdg-open command
This can be used to open the URL if available
gist may support recursively gist all files in a directory by `-r`
for anonymous users, the url returns from gist api is something like https://gist.github.com/7216441 , and it would redirect to https://gist.github.com/anonymous/7216441, it's not easy to get the raw file url by scripting. this commit make the hack to handle the HTTPRedirection, and concate the result url with /raw to generate the raw url.
Unlike `xclip`, calling `xsel` without any argument outputs the selection. In other words, `xclip` defaults to `xclip -i`, but xsel` defaults to `xsel -o`. Thus we should use `xsel -i` instead of `xsel` for copying the url to clipboard.
Adds note about storing multiple tokens.
It's a bit wordy, welcome to word-smithing suggestions.