enable apache2 server as front end for swift

1.install apache and wsgi module
2.config apache2 vhost and wsgi files for proxy,
account, container and object server.
3.refactor apache functions from horizon and swift
into lib/apache

Change-Id: I3a5d1e511c5dca1e6d01a1adca8fda0a43d4f632
Implements: blueprint enable-apache-frontend-for-swift
Merge "enable apache2 server as front end for swift"