Revert "Revert "Hardcode the loggregator server as loggregator.SUBDOMAIN""

This reverts commit 9fa9a33aebfb021758c45b4028dd77e9f4bb5004.
switch from websockets to http chunking

  * removes EM as dependency
  * works with http and https
  * removes need to pass explicit loggregator host

[#53187781, #53718655]

Signed-off-by: Alex Jackson <ajackson@pivotallabs.com>