fix(deps): use angular ~1.2 before migrated to 1.3

Change angular version spec from ">=1.2.*" to "~1.2" to ensure generator
tests run before migration to 1.3 is completed.

Closes #654.
Merge pull request #655 from sigriston/fix-deps-angular-1.2

fix(deps): use angular ~1.2 before migrated to 1.3