Update raw-file URL

[ben]

raw.github.com has been deprecated. This updates the installation instructions to use curl, as well as the raw.githubusercontent.com domain.

[fingolfin]

Switching to curl by default is helpful on OS X, which ships with curl but not wget; so with this change, installation will work "out of the box" there.

The only thing I slightly dislike about this is the commit message. It does not make clear that the README is modified, not git-remote-hg itself. Perhaps this would do:

"README: fix raw github URLs and replace wget by curl

raw.github.com has been deprecated, use raw.githubusercontent.com instead.
Also, use curl instead of wget.
"

[fingolfin]

@ben I cherry picked this into my git-remote-hg fork, with the adjusted commit message; if you are unhappy with that, I will of course change it back and/or change it to something you prefer. See https://github.com/fingolfin/git-remote-hg

[ben]

Looks great to me. I'll close this out. Thanks!

[felipec]

Deprecated? Seems to work fine here.