Add templating to name #41

[KevinJump]

lets you template the package name on pack command.

e.g

umb pack package.xml -v 1.4.3 -n My.Super.Package.{version}.zip

will produce My.Super.Package.1.4.3.zip

lets you template:

• {name} replaced with the name of the package from the package.xml (as now)
• {version} version of the package (either from xml or command line.

the default template if nothing is supplied via the command line is {name}_{value}.zip

fixes issue #41