Optional expose on right click

[Dravenshorst]

Adds the option to disable/enable expose on right click.

[Dravenshorst]

@rlamana I have fixed your concerns. You can now specify the exposeListeners like:

var wm = new Ventus.WindowManager({
  showExposeOn: 'a|enter|space|rightclick'
});

Available listeners are a,enter,space,rightclick, but you can also disable it by setting showExposeOn: 'none'.

If you don't specify anything it will use the default rightclick.

Can you look at it again. Thanks

[Dravenshorst]

@rlamana I have fixed your concerns, can you have look at it again?

[rlamana]

Please resolve the conflicts.

These problems with the dist files should be solved once the branch v0.3.0 is merged. This is a branch where I have been working on a migration to webpack and upgraded a little this old code.

[danimesq]

@Dravenshorst, please solve the conflicts. Appreciate if this PR gets merged.