make peerDep semver more specific

[morganrallen]

Addresses #164

The discussion in that issue doesn't actually hit on the point of what's gone wrong. It appears the order version of semver in npm ~1.4.2x doesn't see <=13 matching 13.0.0. This can be tested with a simple one liner

npm install karma-browserify browserify@~13

This does in fact satisfy the peer dependency but an error is still raised. NPM may or may not fix the issue in that order version but at least this is a local fix that can prevent it.

[nikku]

Merged via fdcbabf

[morganrallen]

Thanks.