define toolbar color and alphas through config.xml

bigbluebutton-client/resources/config.xml.template

bigbluebutton-client/src/org/bigbluebutton/core/vo/Config.as

...ton-client/src/org/bigbluebutton/core/vo/ConfigBuilder.as

...ient/src/org/bigbluebutton/main/model/ConfigParameters.as

...org/bigbluebutton/main/model/modules/ModulesDispatcher.as

...-client/src/org/bigbluebutton/main/views/MainToolbar.mxml