MXS-1300: Build MaxCtrl if npm was found

If npm is installed on the local system, try to build MaxCtrl as a part of
the core.

cmake/FindNPM.cmake

@@ -0,0 +1,16 @@
+# Find the npm executable
+#
+# The following variables are set:
+# NPM_FOUND - True if npm was found
+# NPM_EXECUTABLE - Path to npm
+
+find_program(NPM_EXECUTABLE npm)
+
+if (${NPM_EXECUTABLE} MATCHES "NOTFOUND")
+  message(STATUS "Could not find npm")
+  set(NPM_FOUND FALSE CACHE INTERNAL "")
+  unset(NPM_EXECUTABLE)
+else()
+  message(STATUS "Found npm: ${NPM_EXECUTABLE}")
+  set(NPM_FOUND TRUE CACHE INTERNAL "")
+endif()