Added option to specify modules order at creation time.

[andyepx]

Added an additional option to specify the desired order of modules in the actions bar.

In Editr.vue, the modules function creates a list of all the availableModules and, if a list of modulesOrder is specified, returns the availableModules in that order. If no order it's specified, it behaves as in the current version.

In bus.js, there is a new option modulesOrder that can be set at init time.