Added account integration tests.
Incorporates the Esendex Sandbox project for integration testing.
Removed accidentally included esendex RAML definition.
Fixed incorrect commit SHA for esendex-sandbox.
Switched the esendex-sandbox dependency ref to gh master.
Dropped builds >0.11.13 due to instability, see: polotek/libxmljs#238
Moved integration tests back to the tests directory and tidied gulp scripts.
Fixes issue #8 by adding a socket timeout callback instead of event listener.