MB-6731: Add required modules for docloadgen

Since we remove module workloadgen, we need to make docloadgen
self sufficient to copy all dependent modules during build

Change-Id: I0794705032b0b91b590df84a81594b3d25fd395e
Reviewed-on: http://review.couchbase.org/21118
Reviewed-by: Farshid Ghods <farshid@couchbase.com>
Tested-by: Farshid Ghods <farshid@couchbase.com>

Makefile.am

@@ -1,4 +1,6 @@
-COUCHBASE_PYTHON_LIB = ../couchbase-python-client/couchbase
+COUCHBASE_PYTHON_LIB = ../couchbase-python-client/couchbase \
+                       ../couchbase-python-client/httplib2 \
+                       ../couchbase-python-client/simplejson
 
 default: