2.2.0: adds support for additionally HPE, H3C and Dell server - Fixes minor reporting issues

Features:

• adds support for (#203):
  • H3C UniServer R4900 G6
  • Dell PowerEdge XE9680
  • HPE Cray XD670
  • SuperMicro SYS-122FT
• Thermal reading for Dell iDRAC 9 and newer systems moved to ThermalSubsystem #195

Bugfixes:

• mitigates issue with HPE iLO 6 voltages reported as WARNING #193
• fixes issue with unavailable firmware list #199
• fixes issue if temp state is not a string #199

Possible breaking changes

• enforces performance data label guidelines #197 ("=" and "'" are now converted to "_")