v7.0.0

v7.0.0 (#155)

Major updates
* All init / request / regenerate executables now support single domains - use `-d XXXXXX`
* Adding support for NAXSI web application firewall - use `PROXY_ENABLE_NAXSI=1`

Minor updates
* Using latest base image
* Renaming `PROXY_URI` to `PROXY_DOMAIN` (if you don't rename you'll get a warning in logs but it will still work)
* Adding more debug output

Documentation updates
* Adding new arguments to README