Simple http client to replace boto and cfn-signal

Change-Id: I1fb60673788e59c4864e7bacc115b28e88d69515
Use http_client instead of curl for cfn-signal

Change-Id: Icc4f7633791afd2e8fad5c944fd33ba6e3ac762c
EC2Signer to sign cfn calls.

This is identical to the copy in heat and python-keystoneclient.
A copy is made here to avoid creating a dependency.

Change-Id: Ia4533d1337b56e9fbe2b2d8f5f9c106be556de08
No longer use boto for metadata retrieval

Now makes the request using the minimal httplib based client

Change-Id: I7e64d497179763faabf1192d1a4d5f96679da20b
Method read_one_line_file for server url config

Change-Id: I13463d6646131f4c7adc457a6f6165f1dd98b1cd
A boto-free implementation of put_metric_data

Change-Id: Ibb7569410694bd0e81d0414f8fe5def378c06afe
Remove boto as a dependency

Change-Id: Iff29c4f5e582e30d591dc4a6c9c9c56eed3e64be
use read_one_line_file for metadata config

Change-Id: I9ba92c9c6c974418f4a0b9fc3fb5b6844e459790