Added feature export into app, fixed connections data dir

Tool for exporting model added into app (icon at toolbar). Fixed path
to `connections.json` file.
Added simple input dialog for input table name when new table is created
Fixed assets of exported model, added save/load for it

Exported model now can save/load to/from HTML5 LocalStorage (if it is
available).
Fixed saving of actual table position when it is moved
Fixed displaying columns at TableDialog

Columns displayed at TableDialog should been displayed independetly on
previous displayed table's columns.
Fixed id of the exported app to be realy unique

App id should be name and db id independent (two models can have same).
Added `infoDialog` and it's using at exported model
App restruturalized, added `dm.core` namespace
Adding tools into toolbar moved to main script, added `nib` import
Fixed creating model from JSON and loading at `export` mode