Until we prebuild wheels don't build wheels for deb installed libs

Until we have the ability to prebuild wheels so we don't spend time
compiling them during devstack runs, stop building wheels for libraries
that we still install from deb packages.

Long term we want to move away from using deb packages to install python
packages and use wheels. But until the wheel building logic is in place
so we don't have to compile wheels on each devstack run, don't waste
time compiling python libraries that we just use the packaged version of
anyway.

Change-Id: I962e2cfff223f7ab8efd5766ee0ef22229ab27bf

Author: jogo

files/venv-requirements.txt

@@ -1,10 +1,11 @@
+# Once we can prebuild wheels before a devstack run, uncomment the skipped libraries
 cryptography
-lxml
+# lxml # still install from from packages
 MySQL-python
-netifaces
+# netifaces # still install from packages
 #numpy    # slowest wheel by far, stop building until we are actually using the output
 posix-ipc
-psycopg2
+# psycopg # still install from packages
 pycrypto
 pyOpenSSL
 PyYAML