Add Dzung Tran as co-editor of this spec

Dzung Tran is the editor of W3C SystemInfo API spec,
see http://dev.w3.org/2009/dap/system-info/
Merge pull request #8 from hmin/add-co-editor

Add Dzung Tran as co-editor of this spec
Remove DeviceCapabilityProfile def
Merge pull request #9 from hmin/remove-profile

Remove DeviceCapabilityProfile def
Remove getCapabilities method
Merge pull request #10 from hmin/remove-profile

Remove getCapabilities method
Polish the spec

1. Add description for CPU/Memory attributes
2. Rename DeviceXXX to SystemXXX
Refine the description for StorageUnit interface.
Add 2 code examples for CPU and storage API
Add getAVCodecs for audio and video codecs information and related user
case.
Add acknowledgements section.
Refine the use case for codecs API
Add issue for codecs
Fix race condition issue in storage/display info query and event listening

BUG=https://github.com/sysapps/device-capabilities/issues/14
pass validation
clean up introduction
cleanup abstract
reword sotd
reword security and privacy considerations
tighten the language in the DeviceCapabilities Interface section; add SystemStorageEvent and SystemDisplayEvent interfaces; add required definitions to the conformance section