Start default revision at 1.

It seems to be conventional for deb and rpm to start the revision at 1.

https://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version
https://fedoraproject.org/wiki/Packaging:NamingGuidelines?rd=Packaging/NamingGuidelines#Package_Versioning
Change handling of version, revision and vendor attributes.

After reading some more about versioning for deb and rpm, I belive that
this is more correct.

For debs `<version>+<vendor><revision>` becomes
`<version>-<revision>+<vendor>`.

For rpms `<version>.<vendor><revision>` becomes
`<version>-<revision>.<vendor>`.

This should address the issues seen in #42.
Do not set a default value for vendor.

Should address #42 and #63.