stub out http requests in test

Signed-off-by: Ben Golden <ben@sendgrid.com>
fix Panic -> PanicNotify

Signed-off-by: Ben Golden <ben@sendgrid.com>
Merge pull request #1 from pivotalsendgrid/fix_tests_and_docs

Fix tests and docs
Merge pull request #1 from sendgrid/readmeUpdateAndTestMocks

Readme update and test mocks