fix browser tests for Point and Key

The addUncompressed function is for node-only, and is a temporary workaround
until we expose a better crypto interface in both node and the browser. I wrote
tests for this function that were node-only, but were broken in the browser.  I
also wrote tests for the Point class that should have worked in both node and
the browser, and did, but I was using the wrong module such that it worked only
in node.  This update makes the tests work in the browser by using the correct
module.
Merge pull request #204 from ryanxcharles/feature/fix-browser-tests-for-point-and-key

fix browser tests for Point and Key