Core: Added 'lib/initializers' directory

Before this patch, we used to initialize stuff like database
or mock directories in random places in source code.

This patch should make all initialization happen in one place.
CIMI: If API_VERBOSE is enabled, log into Deltacloud logger

This patch will make sure that logs produced by Sequel (SQL logs)
will go to DeltacloudLogger instead of default Ruby Logger.

The reason is that user can set the '-L/--log' option and redirect
all logs into a file. In that case, this patch will make sure
that SQL logs are saved into that file as well.
Core: Make DeltacloudLogger compatible with Ruby Logger

This patch will make our DeltacloudLogger more compatible
wit the default Ruby 'Logger' class.
Tests: Use 'initializers' in all our tests.

This patch will make possible to run our unit-tests without
initializing the Deltacloud.configure classes, because we already
do that in initializers.

For CIMI tests, this will make sure the database directory exists.
Core: Require 'require_relative' when running in Ruby < 1.9
Tests: Removed warning and references to CIMI-Version header

- Removed couple warnings in DB tests
- Removed all references to CIMI-Version header