Reporting docker deployment improvement

In the patch, I make build pages(landing page ...),
when docker build, when run a container, we can set
the api url(default:testresults.opnfv.org/reporting2) by -e;

For example:
1. In testresults.opnfv.org:
docker run -itd -p 8888:8000 -p 80:80 opnfv/reporting:tag
visit: http://testresults.opnfv.org/reporting2/reporting/index.html

2. Personal use:
docker run -itd -p 8888:8000 -p 80:80 -e SERVER_URL=192.168.131.2:8888 opnfv/reporting:tag
visit: http://192.168.131.2:8888/reporting/index.html

Change-Id: Ib838c12e785151acf9852f25eab254aedc520a1d
Signed-off-by: chenjiankun <chenjiankun1@huawei.com>