OO-1068 bootstrapify file dialog element, improve positioning of callout windows, style table config callout

OO-1068 OO-1113 more bootstrapify of forum, refactor redundant avatar image code, add forum attachment preview

OO-763: don't use the container as reference for collection of components but an interface instead, break the inheritence of Panel and flatted it

OO-373: made the notifications manager robust under concurrent access, write more unit tests to tests the queries on the database and test it under concurrent load

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branch : bps