Extended CI build script

.gitlab-ci.yml

 before_script:
-  - '[[ -d /home/piphone/build ]] || mkdir -p /home/piphone/build'
+  - '[[ -d /srv/piphone/ ]] || mkdir -p /srv/piphone/'
+  - 'which git || (apt-get update -yq && apt-get install git -yqq)'
+  - 'which virtualenv || (apt-get update -yq && apt-get install python3-virtualenv -yqq)'
 stages:
   - install
 
 job install:
   script:
-    - '[[ -d /srv/piphone/sip_backend ]] || mkdir -p /srv/piphone/sip_backend'
-    - (cd /srv/piphone/sip_backend && git clone $CI_BUILD_REPO)
+    - cd /srv/piphone/sip_backend
+    - git clone $CI_BUILD_REPO $CI_PROJECT_NAME
+    - cd $CI_PROJECT_NAME
+    - '[[ -d ./.backend_env ]] || virtualenv --python=python3 .backend_env'
+    - source ./.backend_env/bin/activate
+    - pip install -r requirements.txt
+    - deactivate
   stage: install
-  cache:
-    untracked: true
   tags:
     - piphone
     - ssh