Update Sass-Gems to at least 3.5.2

[dtrunk90]

When trying to compile bootstrap 4.0.0 i get some parsing errors. It seems Bootstrap requires at least 3.5.2: https://github.com/twbs/bootstrap-rubygem/blob/master/bootstrap.gemspec#L16.

[darrinholst]

Unfortunately we'd have to yank compass to do that since it depends on sass < 3.5. I'm not opposed to that, but we are using it to do the compiling. It'd need to change at least here.

[dtrunk90]

As I only need the sass-java-gems package I removed compass and ffi from the gemfile. For compiling I'm using Jawr in conjunction with JRuby. Works like a charm for now.