Code reuse: static files

[ejucovy]

The static files in ./common_static should be audited. Most of them probably don't need to be there.

Of the ones that do need to be there, they should be divided into two groups: ones that are needed for the application itself to function (e.g. ace.js and any diff.js files) and ones that are just used for presentation (e.g. less)

The functionally important ones should be moved inside a static directory within the app directory. The presentational ones should remain at the project level.