Improved docker compose file so can be run for ES6 and ES7 (#23)

* Improved docker compose file so can be run for ES6 and ES7
1. Updated compose file to include the SW_STORAGE env var otherwise it cant be overwritten when which between ES6 and ES7
2. Add missing env var SW_VERSION into env files
3. Updated versions of ES and SW to latest versions for both ES6 and ES7

* Downgrading version of ES 7 due to introduction of SSPL licence to version 7.11

* Removing SW_VERSION so that its not hardcoded to a particular version

Co-authored-by: Andrew Kew <andrew@quadcorps.co.uk>
diff --git a/compose/.env.es6 b/compose/.env.es6
index a2ba582..b19df53 100644
--- a/compose/.env.es6
+++ b/compose/.env.es6
@@ -14,6 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-ES_VERSION=6.8.8
+ES_VERSION=6.8.18
 SW_STORAGE=elasticsearch
-IMAGE_TAG=es6
+IMAGE_TAG=es6
\ No newline at end of file
diff --git a/compose/.env.es7 b/compose/.env.es7
index d2ffb08..b4824c7 100644
--- a/compose/.env.es7
+++ b/compose/.env.es7
@@ -14,6 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-ES_VERSION=7.5.0
+ES_VERSION=7.10.0
 SW_STORAGE=elasticsearch7
-IMAGE_TAG=es7
+IMAGE_TAG=es7
\ No newline at end of file
diff --git a/compose/docker-compose.yml b/compose/docker-compose.yml
index 2eb19a5..a21ea43 100644
--- a/compose/docker-compose.yml
+++ b/compose/docker-compose.yml
@@ -56,7 +56,7 @@
       retries: 3
       start_period: 40s
     environment:
-      SW_STORAGE: elasticsearch
+      SW_STORAGE: ${SW_STORAGE}
       SW_STORAGE_ES_CLUSTER_NODES: elasticsearch:9200
       SW_HEALTH_CHECKER: default
       SW_TELEMETRY: prometheus