Move version script dependencies to a script
Move version script dependencies to a script

Listing the dependencies for the version scripts (preversion, version,
and postversion) in devDependencies means installing a lot of
unnecessary dependencies in the common case (most importantly for
contributors and CI servers).  Since these are only required for
maintainers running `npm version`, install them using a script.  This
also allows for global installation by adding the -g option when running
the script.

Note:  The current version dependencies probably don't justify this, but
I am about to add more.

Signed-off-by: Kevin Locke <ffb4761cba839470133bee36aeb139f58d7dbaa9@kevinlocke.name>

kevinoid/stream-compare,kevinoid/swagger-spec-validator,kevinoid/stream-compare,kevinoid/appveyor-status,kevinoid/node-project-template,kevinoid/stream-compare,kevinoid/swagger-spec-validator,kevinoid/appveyor-status,kevinoid/travis-status,kevinoid/git-branch-is,kevinoid/travis-status,kevinoid/node-project-template,kevinoid/appveyor-status,kevinoid/git-branch-is,kevinoid/travis-status,kevinoid/promised-read,kevinoid/swagger-spec-validator,kevinoid/git-branch-is,kevinoid/promised-read,kevinoid/node-project-template,kevinoid/promised-read