v0.6.0

• #17 separate connection creation from sign-in (bjmllr)
• #16 use VCR to record test interactions on 3.x and 4.x (skrobul)
• #15 enable travisci (skrobul)
• #14 relax restriction on HTTPClient gem (bjmllr)
• #13 added docker testing environments (bjmllr)
• #12 fix an issue with zenoss 4.2.5 (ThomasRasmussen)
• #10 add method to rename devices (skrobul)
• #7 added unit tests (dpetzel)
• #7 relax restriction on JSON gem (dpetzel)
• and various minor fixes and tidy-ups