v0.1.1: Fixing versioning of releases to get rid of `v` in files (#20)

* Fixing versioning of releases to get rid of `v` in files

Current releases had `v` in all the files which is against a current standard.
Therefore, we should remove this.

* Changing tarball non-standard binary names

Solving issue #19 to make tarballs contain standard binary names and removing the redundant /binaries directory

Test:
build the tarbals with `./build_tarballs.sh`
and checked the tarball contents:
```
vagrant@ubuntu-xenial:~/repos/nvdtools/release$ tar zvft nvdtools-4.4.4-linux-amd64.tar.gz
-rwxrwxr-x vagrant/vagrant 3513959 2019-01-24 00:36 cpe2cve
-rwxrwxr-x vagrant/vagrant 2233700 2019-01-24 00:36 csv2cpe
-rwxrwxr-x vagrant/vagrant 8595732 2019-01-24 00:36 nvdsync
-rwxrwxr-x vagrant/vagrant 2229430 2019-01-24 00:36 rpm2cpe
```