Removing npm-shrinkwrap

Good idea in theory, but trips people up when updating `package.json`, plus looks like macs cant create one when it has a `postinstall` (https://github.com/paulmillr/chokidar/issues/92), and doesn't seem to have solved our team city build problems (http://teamcity.gudev.gnl:8111/viewLog.html?buildId=174571&buildTypeId=bt1216&tab=buildLog) 

Any objections?