database: rename installed_extensions_for

Views support activating packages, so rename the method because it will
soon query what is activated versus what is installed.

lib/spack/spack/cmd/deactivate.py

@@ -59,7 +59,7 @@ def deactivate(parser, args):
     if args.all:
         if pkg.extendable:
             tty.msg("Deactivating all extensions of %s" % pkg.spec.short_spec)
-            ext_pkgs = spack.store.db.installed_extensions_for(spec)
+            ext_pkgs = spack.store.db.activated_extensions_for(spec)
 
             for ext_pkg in ext_pkgs:
                 ext_pkg.spec.normalize()

lib/spack/spack/cmd/extensions.py

@@ -90,7 +90,7 @@ def extensions(parser, args):
     # List specs of installed extensions.
     #
     installed = [s.spec
-                 for s in spack.store.db.installed_extensions_for(spec)]
+                 for s in spack.store.db.activated_extensions_for(spec)]
 
     print
     if not installed:

lib/spack/spack/database.py

@@ -741,7 +741,7 @@ def installed_relatives(self, spec, direction='children', transitive=True):
         return relatives
 
     @_autospec
-    def installed_extensions_for(self, extendee_spec):
+    def activated_extensions_for(self, extendee_spec):
         """
         Return the specs of all packages that extend
         the given spec