Add a re-frame example application option

[RadicalZephyr]

Includes a useful pattern for tracing the execution of a re-frame application.

Fixes #43

[sihingkk]

What are stoping us from merging that? can I help somehow?

[martinklepsch]

@sihingkk @RadicalZephyr sorry for letting this sit for so long. I guess now that re-frame-trace got renamed to re-frame-10x we should update those deps/requires in the examples?

[RadicalZephyr]

@martinklepsch done. It appears to work, but there are a few warnings printed out during cljs compilation. I'm not really sure if including the tools.reader dependency is the right thing to do either, but it silenced one warning at least.