Include zapp version in `.zapp` filename on `zpm bundle`

[larsbutler]

The ZPA spec suggests a naming convention for zapps. It might be useful to include the version (from the zapp.yaml) in the build .zapp filename.

For example, a zapp called foo with version 0.2-1 would result in a foo-0.2-1.zapp file on zpm bundle.

[mgeisler]

This implies that we will have to restrict version numbers so they cannot contain / and \. Alternatively, we will have to map these characters to something else when we form for filename.

[larsbutler]

Yeah, I'm in favor of restricting the version numbers to a certain pattern. Something like the debian version scheme would be a good place to start. We could do something similar.