v2.1.1

• chore(package): update (c52eabc)
• fix(instrumentation/https): add https instrumentation (2a44c7c)
• test(cls,tracer): cover with tests (70c198e)
• test(instrumentation/express): cover (be1a4be)
• test(instrumentation/expressError): add tests (8795641)
• test(instrumentation/http): cover with tests (2a9bbbc)
• docs(readme): add travis badge (ed39285)