Get Rid of nobuild, nolink, and alldeps (#2765)

* Removing the nobuild, nolink, and alldeps dependency types in favor of being explicit.
* This will help with maintenance going forward, as adding more dependency types won't affect existing declared dependencies in weird ways.
* default deptype is still `('build', 'link')`

var/spack/repos/builtin/packages/nwchem/package.py

@@ -41,7 +41,7 @@ class Nwchem(Package):
     depends_on('mpi')
     depends_on('scalapack')
 
-    depends_on('python@2.7:2.8', type=nolink)
+    depends_on('python@2.7:2.8', type=('build', 'run'))
 
     # patches for 6.6-27746:
     urls_for_patches = {