change to buildscript as to how docs are created

docs/requirements.txt

@@ -1,11 +1,27 @@
 backports.ssl-match-hostname==3.4.0.2
-docker-py==1.3.0
+bcrypt==2.0.0
+cffi==1.1.2
+characteristic==14.3.0
+colorama==0.3.3
+cryptography==0.9.3
+docker-py==1.3.1
+docopt==0.6.2
+enum34==1.0.4
+idna==2.0
+ipaddress==1.0.14
+paradrop==0.1.1
+pdtools==0.1.35
+pyasn1==0.1.8
+pyasn1-modules==0.0.6
+pycparser==2.14
+pyOpenSSL==0.15.1
+PyYAML==3.11
 requests==2.7.0
-ipaddress==1.0.7
+service-identity==14.0.0
 six==1.9.0
 Twisted==15.2.1
+txdbus==1.0.11
 websocket-client==0.32.0
 wget==2.2
-txdbus==1.0.11
 wheel==0.24.0
 zope.interface==4.1.2

pdbuild.sh

@@ -118,6 +118,7 @@ docs() {
     virtualenv buildenv/env
     source buildenv/env/bin/activate
 
+    rm docs/requirements.txt
     pip install -e ./paradrop
     pip freeze | grep -v 'pex' | grep -v 'paradrop' > docs/requirements.txt
 }