Don't quote GEOSERVER_JAVA_OPTS in .env (#503)

Quoted JAVA_OPTS causes issues in Docker Swarm deploys: the whole value is
parsed and passed to Java as a single option.

Co-authored-by: Giovanni Allegri <giohappy@gmail.com>

.env.sample

@@ -108,7 +108,7 @@ OGC_REQUEST_POOL_CONNECTIONS=10
 # Java Options & Memory
 ENABLE_JSONP=true
 outFormat=text/javascript
-GEOSERVER_JAVA_OPTS='-Djava.awt.headless=true -Xms4G -Xmx4G -Dgwc.context.suffix=gwc -XX:+UnlockDiagnosticVMOptions -XX:+LogVMOutput -XX:LogFile=/var/log/jvm.log -XX:PerfDataSamplingInterval=500 -XX:SoftRefLRUPolicyMSPerMB=36000 -XX:-UseGCOverheadLimit -XX:ParallelGCThreads=4 -Dfile.encoding=UTF8 -Djavax.servlet.request.encoding=UTF-8 -Djavax.servlet.response.encoding=UTF-8 -Duser.timezone=GMT -Dorg.geotools.shapefile.datetime=false -DGS-SHAPEFILE-CHARSET=UTF-8 -DGEOSERVER_CSRF_DISABLED=true -DPRINT_BASE_URL={geoserver_ui}/geoserver/pdf -DALLOW_ENV_PARAMETRIZATION=true -Xbootclasspath/a:/usr/local/tomcat/webapps/geoserver/WEB-INF/lib/marlin-0.9.3-Unsafe.jar -Dsun.java2d.renderer=org.marlin.pisces.MarlinRenderingEngine'
+GEOSERVER_JAVA_OPTS=-Djava.awt.headless=true -Xms4G -Xmx4G -Dgwc.context.suffix=gwc -XX:+UnlockDiagnosticVMOptions -XX:+LogVMOutput -XX:LogFile=/var/log/jvm.log -XX:PerfDataSamplingInterval=500 -XX:SoftRefLRUPolicyMSPerMB=36000 -XX:-UseGCOverheadLimit -XX:ParallelGCThreads=4 -Dfile.encoding=UTF8 -Djavax.servlet.request.encoding=UTF-8 -Djavax.servlet.response.encoding=UTF-8 -Duser.timezone=GMT -Dorg.geotools.shapefile.datetime=false -DGS-SHAPEFILE-CHARSET=UTF-8 -DGEOSERVER_CSRF_DISABLED=true -DPRINT_BASE_URL={geoserver_ui}/geoserver/pdf -DALLOW_ENV_PARAMETRIZATION=true -Xbootclasspath/a:/usr/local/tomcat/webapps/geoserver/WEB-INF/lib/marlin-0.9.3-Unsafe.jar -Dsun.java2d.renderer=org.marlin.pisces.MarlinRenderingEngine
 
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 # Security