Fix Gate: Force pip2 instead of pip

Something appears to have caused the xenial guests to install all
python libraries into python 3.5 directories and therefore the guest
won't launch. This change forces pip2 and in theory should get around
that.

Moved Redis and PostgreSQL installs after the trove-dep ones.

Change-Id: I3bbe3bafa7ea3e627272103ac16a38f6a32a8a06
Partial-Bug: #1650382

integration/scripts/files/elements/ubuntu-cassandra/install.d/10-cassandra

@@ -16,9 +16,9 @@ apt-get install -qy python-migrate build-essential
 apt-get install dsc21=2.1.* cassandra=2.1.* -qy
 
 # The Python Driver 2.0 for Apache Cassandra.
-pip install cassandra-driver
+pip2 install cassandra-driver
 # Sorted sets support for the Python driver.
-pip install blist
+pip2 install blist
 
 service cassandra stop
 rm -rf /var/lib/cassandra/data/system/*

integration/scripts/files/elements/ubuntu-guest/install.d/15-trove-dep

@@ -24,8 +24,8 @@ if [ -f ${TMP_HOOKS_DIR}/upper-constraints.txt ]; then
     UPPER_CONSTRAINTS=" -c ${TMP_HOOKS_DIR}/upper-constraints.txt"
 fi
 
-pip install -q --upgrade -r ${TMP_HOOKS_DIR}/requirements.txt ${UPPER_CONSTRAINTS}
+pip2 install -q --upgrade -r ${TMP_HOOKS_DIR}/requirements.txt ${UPPER_CONSTRAINTS}
 
 echo "diagnostic pip freeze output follows"
-pip freeze
+pip2 freeze
 echo "diagnostic pip freeze output above"

integration/scripts/files/elements/ubuntu-mongodb/install.d/25-trove-mongo-dep

@@ -6,4 +6,4 @@
 set -e
 set -o xtrace
 
-pip install pymongo>=3.0.2,!=3.1
+pip2 install pymongo>=3.0.2,!=3.1

integration/scripts/files/elements/ubuntu-postgresql/install.d/30-postgresql

@@ -76,4 +76,4 @@ apt-get remove -y $dev_pkgs
 
 # Install the native Python client.
 apt-get -y install libpq-dev
-pip install psycopg2
+pip2 install psycopg2

integration/scripts/files/elements/ubuntu-redis/install.d/30-redis

@@ -45,9 +45,9 @@ ULIMIT=65536
 _EOF_
 
 # Install Python driver for Redis ('redis-py').
-pip install redis
+pip2 install redis
 
 # By default, redis-py will attempt to use the HiredisParser if installed.
 # Using Hiredis can provide up to a 10x speed improvement in parsing responses
 # from the Redis server.
-pip install hiredis
+pip2 install hiredis