Add JSON responses to Network and Subnet models

Signed-off-by: Tomas Sedovic <tomas@sedovic.cz>
Fix Network and Subnet create routes for JSON

Creating a network or subnet whilst using "Accept: application/json"
resulted in an exception because of the missing `xml_to_json` method in
the routes for JSON responses.

Signed-off-by: Tomas Sedovic <tomas@sedovic.cz>
JSON support for network_interface model

Signed-off-by: Tomas Sedovic <tomas@sedovic.cz>
Site - update links for community call #20
Core: Added initializer to preload all drivers

This patch should fix all nasty Thread issues with 'require'
or 'require_relative'. Driver classes are reloaded so there is
not need to call 'require_relative' in thread-not-safe context.
CIMI: Fixed minor test failures
Core: Deltacloud::Library must require models/drivers separately.
Fixed MRI 1.9.3p194 issues
CIMI - Add support for $expand on cloudEntryPoint
Addresses Jira DTACLOUD-502
Changes needed to adapt to using a hash to contain all root entry
point, vs the acts_as_root_entity method.
Refactor service/cloud_entry_point.rb based on input from Michal Fojtik.
Huge Thanks! Michal Fojtik!
CIMI - Remove credentialTemplates from CEP COLLECTIONS.
       Use ruby style hash iteration on CEP COLLECTIONS.
       Fix typos uncovered during testing.

       These changes address review feedback from Michal Fojtik.
Site: Add description of git pull request workflow