ext/boto and ext/botocore: fails to export spans via jaeger

[ThePumpingLemma]

Describe your environment

opentelemetry-api = "=0.9b0"
opentelemetry-ext-boto = "=0.9b0"
opentelemetry-ext-botocore = "=0.9b0"
opentelemetry-ext-dbapi = "=0.9b0"
opentelemetry-ext-jaeger = "=0.9b0"
opentelemetry-ext-psycopg2= "=0.9b0"
opentelemetry-ext-requests = "=0.9b0"
opentelemetry-instrumentation = "=0.9b0"
opentelemetry-sdk = "=0.9b0"
python = "=3.7.4"

Steps to reproduce
Install and enable ext/boto with a jaeger exporter configured

What is the expected behavior?
Spans are exported via jaeger

What is the actual behavior?

Traceback (most recent call last):
  File "/opt/cadre/web/.venv/lib/python3.7/site-packages/opentelemetry/sdk/trace/export/__init__.py", line 80, in on_end
    self.span_exporter.export((span,))
  File "/opt/cadre/web/.venv/lib/python3.7/site-packages/opentelemetry/ext/jaeger/__init__.py", line 156, in export
    jaeger_spans = _translate_to_jaeger(spans)
  File "/opt/cadre/web/.venv/lib/python3.7/site-packages/opentelemetry/ext/jaeger/__init__.py", line 200, in _translate_to_jaeger
    tags.extend(_extract_tags(span.resource.labels))
AttributeError: 'str' object has no attribute 'labels'

Additional context
Span creation code stomps the resource field with a string, which is not the expected type of Resource:

• opentelemetry-python/ext/opentelemetry-ext-boto/src/opentelemetry/ext/boto/__init__.py

  Line 126 in 0ce8cb6

  span.resource = "%s.%s" % (endpoint_name, http_method.lower())

• opentelemetry-python/ext/opentelemetry-ext-botocore/src/opentelemetry/ext/botocore/__init__.py

  Line 101 in 0ce8cb6

  span.resource = "%s.%s" % (endpoint_name, operation.lower())

Not sure what the intent is here, but maybe resource should be an attribute instead?