Config.xml XML Schema reworked

Config.xml XML Schema reworked

[Issue#]       LINUXWRT-314
[Feature]      Schema reworked base on: dev.w3.org/2006/waf/widgets-schema/
[Cause]        N/A
[Solution]
 1. xsd files were substituted with schema received from convertion
    of http://dev.w3.org/2006/waf/widgets-schema/tests/ relax NG syntax.
 2. Tizen changes were applied as in old config.xsd
 3. Some restrictions have been removed for purpose of tests
[Verification] Validate xml schema: xmlstarlet val -e configuration/widgets.xsd configuration/config.xml
 Check xml schema content.

Change-Id: I960fbd393ce144ab9acf5b67cdafa219ecc435dc