Add bidi support

People may post events in different languages among which some may use RTL ones. Since Mobilizon works in federation, it should be able to handle both RTL and LTR text and render it in correct direction. This can be done by adding bidirectional text support.

In most cases, adding dir="auto" attribute to relevant html tag would do most of the trick. Rest would be about using different css instead of left|right values for text-align or margin/padding.