Updated rpmbuild spec file version 0.13

rpm build spec: Updated to 0.13-release

### Change:
- Updated to 0.13-release

### Distro support
- Fedora 19 x86_64

### How to build
    $ sudo yum install rpm-build groovy unzip java-1.7.0-openjdk gcc ruby
    $ rpmdev-setuptree
    $ spectool -g -R contrib/rpm /groovyserv.spec
    $ rpmbuild --clean -ba contrib/rpm /groovyserv.spec
    $ sudo yum install ~/rpmbuild/RPMS/x86_64/groovyserv-0.XX-X.fc19.x86_64.rpm --nogpgcheck

### How to use
    $ /opt/groovyserv/bin/groovyclient -e "println('Hello, GroovyServ.')"

or

    $ export GROOVYSERV_HOME=/opt/groovyserv
    $ groovyclient -e "println('Hello, GroovyServ.')"