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/r-markdown/package.py

@@ -38,4 +38,4 @@ class RMarkdown(RPackage):
 
     version('0.7.7', '72deca9c675c7cc9343048edbc29f7ff')
 
-    depends_on('r-mime', type=nolink)
+    depends_on('r-mime', type=('build', 'run'))