Add gemspec

Refer to prawn ~>1

prawn-forms.gemspec

@@ -0,0 +1,16 @@
+PRAWN_FORMS_VERSION = "0.1.1"
+
+Gem::Specification.new do |spec|
+  spec.name = "prawn-forms"
+  spec.version = PRAWN_FORMS_VERSION
+  spec.platform = Gem::Platform::RUBY
+  spec.summary = "A fast and nimble PDF generator for Ruby"
+  spec.files = Dir.glob("{examples,lib,data}/**/**/*") +
+                      ["prawn-forms.gemspec"]
+  spec.require_path = "lib"
+  spec.required_ruby_version = '>= 1.8.7'
+  spec.required_rubygems_version = ">= 1.3.6"
+
+  spec.extra_rdoc_files = %w{CHANGELOG README.markdown MIT-LICENSE}
+  spec.add_dependency('prawn', '1.0.0.rc1')
+end