Pin pip and update setuptools in Dockerfile

Changes to pip and/or setuptools caused the building of the Docker
image to fail with an error like this:

```
error in pytango setup command: 'install_requires' must be a string
or list of strings containing valid project/version requirement
specifiers
```

Older pip and new setuptools is working.  Also removed `tango-admin`
package - not sure why it was there since it is related to Django,
not TANGO Controls.  It was also failing to install.

docker/Dockerfile

@@ -38,8 +38,9 @@ RUN apt-get install -y --force-yes \
 # Remove some packages from the base template
 RUN apt-get -y purge postfix
 
-# Upgrade pip to latest
-RUN pip install --upgrade pip
+# Upgrade pip to latest version that works nicely on Ubuntu 14.04
+# Also need a more recent version of setuptools
+RUN pip install --upgrade 'pip<10' setuptools
 
 # Installing ansible
 RUN add-apt-repository -y ppa:ansible/ansible
@@ -116,12 +117,10 @@ RUN pip install enum34 \
 
 # Pip install itango cli
 RUN pip install itango \
-                "six>=1.9.0" \
-                tango-admin
+                "six>=1.9.0"
 
 # Install tango java tools like pogo and jive
-RUN apt-get update \
- && apt-get install -y default-jre \
+RUN apt-get install -y default-jre \
                        liblog4j1.2-java
 RUN wget 'https://people.debian.org/~picca/libtango-java_9.2.5a-1_all.deb' -P /tmp/ \
  && dpkg -i /tmp/libtango-java_9.2.5a-1_all.deb \