Solving the multiple chart problem in the most straightforward way. Note...

... that I could make it more resilient to more charts being added in show.html, but not worth it [1], given that the chart view will be entirely re-written to be on the front end later on anyways. @wilo99: please note that inserting more than one chart block into show.html will create a bug at the moment.

[1] - I already spent an hour or so messing around with enlive, and its not straightforward, and requires re-writing the html a bit. Given that its going to be redone in Om, doesn't seem worth the trouble.

Closes #568