Release v0.6.14

• sperf was not parsing new byte eviction format as of in sperf filtercache as
  of DSE 5.1.17, 6.0.10, 6.7.5 and 6.8.0
• new makefile for build dependencies
• updated changelog to be accurate
• sperf version outputs changelog and version
• removed support and testing for Python 3.6
• sperf script will now bomb if python 3.7 or greater is not installed