Move version info to the module

This will help with packaging as the gemspec can be extracted
without having VERSION file around.
Do not depend a git repository when parsing gemfile

Addressing:
+ rake test
rake aborted!
There was a Errno::ENOENT while loading openscap.gemspec:
No such file or directory - git from
  /builddir/build/BUILD/openscap-0.2.0/usr/share/gems/gems/openscap-0.2.0/openscap.gemspec:22:in ``'
  /builddir/build/BUILD/openscap-0.2.0/usr/share/gems/gems/openscap-0.2.0/Rakefile:3:in `<top (required)>'
Specify gemname to enable test run during scl build

Addressing:
rake aborted!
Unable to determine name from existing gemspec. Use :name => 'gemname' in #install_tasks to manually set it.
/opt/rh/ruby193/root/usr/share/gems/gems/bundler-1.3.5/lib/bundler/gem_helper.rb:30:in `initialize'
/opt/rh/ruby193/root/usr/share/gems/gems/bundler-1.3.5/lib/bundler/gem_helper.rb:14:in `new'
/opt/rh/ruby193/root/usr/share/gems/gems/bundler-1.3.5/lib/bundler/gem_helper.rb:14:in `install_tasks'
/root/rpmbuild/BUILD/openscap-0.2.1/opt/rh/ruby193/root/usr/share/gems/gems/openscap-0.2.1/Rakefile:3:in `<top (required)>'
Let's pervert my name ...

to support gem build with ruby193 on Red Hat Enterprise Linux 6

Addressing:
Exception `ArgumentError' at /opt/rh/ruby193/root/usr/share/ruby/psych/scalar_scanner.rb:91 - invalid value for Integer(): "\xC5\xA0imon Luka\xC5\xA1\xC3\xADk"
invalid byte sequence in US-ASCII
ERROR:  While executing gem ... (ArgumentError)
    invalid byte sequence in US-ASCII
ruby-openscap-0.3.0