Use webpack and move parsing code to st_exp_protobuf

[eriksjolund]

The file
osd-spot-viewer/from_layout/src/entry.js
contains parsing code that should be moved to
https://github.com/eriksjolund/st_exp_protobuf/tree/master/javascript

The files
osd-spot-viewer/from_layout/*.proto
should be removed as they were copied from
https://github.com/eriksjolund/st_exp_protobuf/tree/master/protobuf_schema

Instead we should start to use the buildtool webpack and somehow start
to depend on st_exp_protobuf.

When we start to use webpack we should also split the file
osd-spot-viewer/from_layout/src/entry.js
to separate out different functionality components into multiple files.

Webpack seems to be the standard build tool right now. For instance
https://medium.com/javascript-and-opinions/state-of-the-art-javascript-in-2016-ab67fc68eb0b#.540xtnn1v
recommends it.