Verifying that our tracecontext is compliant with the w3c
tracecontext reference is valuable. Adding a tox command
to verify that the TraceContext propagator adheres to the
w3c spec.

As the tracecontext spec calls for the creation of new, valid
spans in the case of recieving invalid data from headers,
it is necessary to have functions that generate valid span
and trace ids.

…m ones.

This fixes all the errors, leaving 6 failures.

The tracecontexthttptextformat now adheres completely to the w3c
tracecontext test suite.

moving the test endpoint to a non-root, to
ensure that the basic example is clear.

Adding unit tests to test_tracecontexhttptextformat
that were helpful.

moving the generate span / trace id methods back to API. no longer needed due to open-telemetry#235

moving test service to it's own module.

modifying shell script to use bourne shell, using posix standard location

Ensuring resources installed to the target directory are not included
in style and linting.

Modifying tox invocation to include python version to ensure it's
called by travis-ci.

Fixing tests that are no longer valid due to previous changes (
tracecontext returning INVALID_SPAN, start_as_current_span called)