converted imagesize plugin to lib

lib/imagesize/imagesize.gemspec

@@ -0,0 +1,15 @@
+Gem::Specification.new do |s|
+  s.name        = 'imagesize'
+  s.description = 'measure image size(GIF, PNG, JPEG ,,, etc) code by Pure Ruby'
+  s.summary     = 'Imagesize will detect and measure images in the following formats: GIF, PNG, JPEG, BMP, PPM, PGM, PBM, XBM, TIFF, XPM, PSD, SWF'
+
+  s.version = '0.1.2'
+  s.date    = '2010-10-02'
+
+  s.author   = 'Keisuke Minami'
+  s.email    = 'keisuke@rccn.com'
+  s.homepage = 'http://rubygems.org/gems/imagesize'
+
+  s.files        = `git ls-files`.split("\n")
+  s.require_path = 'lib'
+end