用rpmbuild指令來建立RPM

Reference:
1. rpm guide, http://fedora.linuxsir.org/fedoradocs/rpm-guide/en/
2. rpmbuild,  http://fedora.linuxsir.org/fedoradocs/rpm-guide/en/ch08s02.html#id2831050
3. rpmbuild基礎教學, http://www.puritys.me/docs-blog/article-71