Set `grunt.util.linefeed` for `copyAndProcess()`

`copyAndProcess()` converts line endings on Windows as mentioned in
issue #42. This should be configurable.

`grunt.template.process` uses `grunt.util.normalizelf()`, and this
function looks `grunt.util.linefeed` for line endings normalization;
therefore setting this property fixes a problem on Windows.

I think Git's [`core.autocrlf`][1] configuration helps to determine
whether `grunt-init` should normalize LF or not. If this configuration
is `input` or `true`, there is no problem with LF normalization.

`grunt-init` should set `grunt.util.linefeed` to `\n` when
`core.autocrlf` is `false` for preventing LF normalization.

[1]: http://git-scm.com/book/en/Customizing-Git-Git-Configuration#Formatting-and-Whitespace