[DLNA] Add sort options for MediaServer example

This patch adds sorting options to mediaserver.html
[Application] Add current application exit/hide support

The supported APIs are listed below:
Application.hide/exit

The implementation leverages running application object exported by the runtime
process on the DBus session. The "Terminate" and "Exit" methods of it only
permit the launcher process to access.

Supplement Application example for new added APIs are also added.
Merge pull request #289 from seanlong/app_dev

[Application] Add current app exit/hide support
Bump version to 0.50
[Tizen] Don't throw exception when empty files are read

This patch removes check that throws exception when empty file is read.
Merge pull request #293 from alexshalamov/fix_read_empty_file

[Tizen] Don't throw exception when empty files are read
Bump version to 0.51
[Tizen] Move MediaServer dbus objects to worker thread

This patch adds new worker thread with g_main_loop for async
dbus call processing.
Merge pull request #262 from alexshalamov/add_sort_options

[DLNA] Add sort options for MediaServer example
Bump version to 0.52
[Content] Update instance counter in anycase

Update the instance counter in any case and not just when connected sucesfully
to the database. Otherwise, the assert will cause crash in dtor later on.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1599
Merge pull request #294 from poussa/xwalk-1599

[Content] Update instance counter in anycase
[Application] Add application metadata support

Below APIs are added:
ApplicationMetaData
ApplicationManager.getAppMetaData

Application metadata is specified in config.xml and can be readonly
accessed by both native and web applications.

BUG=XWALK-1610
Bump version to 0.53
Merge pull request #295 from seanlong/app_dev

[Application] Add application metadata support
Add OWNERS
Merge pull request #296 from halton/owner

Add OWNERS
Bump version to 0.54
Merge pull request #291 from alexshalamov/add_worker_thread_to_mediaserver

[Tizen] Move MediaServer dbus objects to worker thread
[Tizen] Add support for missing virtual roots

This patch adds support for missing virtual roots:
wgt-package, wgt-private, wgt-private-tmp and ringtones.