update ffho-site-auto-select

site.conf is now called site.json in gluon-master, because of the json-format

fix Makefile
use luci-lib-json instead ob luci-lib-jsonc
remove obsolete sites.lua
fix and improve 005-set-site-config

In actual gluon master the site.conf is converted to site.json during build, so the created site.conf has to be stored as site.json. Additionally the conversion during build is done for the associated config files, too.
Actually the following config files are used by this programm:
- $(GLUON_SITEDIR)/site.conf -> /lib/gluon/site-select/default.json
  - the default site-config
  - is used as basis for new generated sites
- $(GLUON_SITEDIR)/extra/sites.conf -> /lib/gluon/site-select/sites.json
  - contains the individual site-config for each site
  - these changes are added to the default site
- $(GLUON_SITEDIR)/extra/groups.conf -> /lib/gluon/site-select/groups.json (if file exists)
  - with this file you can define some individual config for a group of sites
  - changes are applied to default site, before sites.json
  - set site_select.group='group_x' in sites.conf for each site, which should use a group called group_x

split ffho-config-mode-site-select in:
- ffho-config-mode-site-select (for the UI, needs ffho-site-generate)
- ffho-site-generate (for the site-generation)
- ffho-upgrade-tools (for migration-scripts)

split ffho-config-mode-geo-location in:
- ffho-config-mode-geo-location
- ffho-upgrade-tools (for migration-scripts)