Add gemspec file
Add gemspec file

I'm about to push Import-JS as a gem. This will make it easier for
others that don't use VIM to integrate with their editors.

I tested that this gemspec is somewhat correct by doing this:

  > gem build import_js.gemspec
  > gem install import_js-0.0.1.gem
  > irb
  irb(main):001:0> require 'import_js'
  => true
  irb(main):002:0> ImportJS::Importer.new
  => #<ImportJS::Importer:0x007f9bed00d0a8
  @config=#<ImportJS::Configuration:0x007f9bed 00d058 @config_time=nil,
  @config={"aliases"=>{}, "declaration_keyword"=>"var", "exclu des"=>[],
  "jshint_cmd"=>"jshint", "lookup_paths"=>["."]}>,
  @editor=#<ImportJS::VIMEdi tor:0x007f9bed00d080>>

trotzig/import-js,Galooshi/import-js,lencioni/import-js,trotzig/import-js,lencioni/import-js,trotzig/import-js,lencioni/import-js