Correct the version to 2.0.0-alpha.4
Correct the version to 2.0.0-alpha.4

According to [semver #9](http://semver.org), the prerelease version uses a hyphen.
rainforestapp/susy,rajkaushik05/susy,gonsakon/susy,pairyo/susy,rainforestapp/susy,Sapphire64/susy,kaij/susy,katoffsky/susy,greyhwndz/susy,pairyo/susy,gabskoro/susy,gabskoro/susy,katoffsky/susy,briangonzalez/susy,rajkaushik05/susy,kraftner/susy,webdev1001/susy,kaij/susy,greyhwndz/susy,kaij/susy,rainforestapp/susy,kraftner/susy,rajkaushik05/susy,oddbird/susy,gonsakon/susy,BionicClick/susy,ericam/susy,ericam/susy,MichaelArestad/susy,oddbird/susy,Sapphire64/susy,briangonzalez/susy,ericam/susy,katoffsky/susy,MichaelArestad/susy,kraftner/susy,pairyo/susy,Sapphire64/susy,webdev1001/susy,gabskoro/susy,BionicClick/susy,BionicClick/susy,greyhwndz/susy