[added] support for Fedora >= 27

Fixed issue with new Influx version numbering

add independent build option for docker build

reversed versioning for collectd-opentsdb

Double/single brackets should be the other way around for versions greater than 0.11

Docker Improvements

Updates

optionally install python client

- add influxdb_bind_hostname var (defaults to ansible_hostname )
- deal w/ config format changes

Fix collectd and opentsdb brackets

added brackets to collectd and opentsdb for compatibility with 0.13

Removed peer data purge from cluster-test.yml to avoid confusion (and accidental destruction of data).

Modified cluster purge logic slightly (due to extra/dirty data being kept in the WAL). Added sane, non-destructive defaults.