jsgui: Replace _.template with custom function that strips comments

Makes the source much more readable. Before:
![screen shot 2014-09-26 at 18 48 39](https://cloud.githubusercontent.com/assets/837527/4425034/67da2018-45a5-11e4-8041-43486b1ea6b3.png)
After:
![screen shot 2014-09-26 at 18 45 43](https://cloud.githubusercontent.com/assets/837527/4425006/07877b70-45a5-11e4-9aca-54c0c1340964.png)

The rendered page itself still contains the Apache license header at the top.

Do we want to replace `_.template` or add an alternate function for use with templates likely to contain a license header? I figured the former saves having to replace lots of function calls and will automatically include all templates added in the future.