PKGBUILD fixing and cleanup

Matching the guidelines from https://wiki.archlinux.org/index.php/VCS_PKGBUILD_Guidelines#Git

You should consider renaming the package cmdevcenter-git. This is why I used _pkgname in the script.
To do that, I think you have to submit a package with the pkgname cmdevcenter-git and [email the TUs](https://mailman.archlinux.org/mailman/listinfo/aur-general) to ask them to merge the packages.