Make BottomBar resize when change visibility of BottomBarTab to GONE

[arturgaleno]

As discussed at #437 No more dynamic adding of tabs?.

Was suggestioned this piece of code:
bottomBar.getTabAtPosition(x).setVisibility(View.GONE);
to make tab gone dynamically.

But, when we use that, tabs don't get resized on BottomBar.

This PR comes to solve this issue and added this enhancement.

Thanks!

[coveralls]

Coverage decreased (-1.0%) to 54.902% when pulling dd90a98 on arturgaleno:master into 3118116 on roughike:master.

[yombunker]

@arturgaleno is this still a thing on the latest version?

[arturgaleno]

@yombunker I really don't know. But, it's very simple to reproduce that behavior. Simple create a bottom bar with xml and then set any tab to gone. The bottom bar must resize it's content appropriately.

[yombunker]

@arturgaleno i don't think this is how is supposed to be done, i'm pretty sure you are suppose to change the items send to the BottomBar instead of making it "gone" programmatically and expecting to resize. @roughike can you chime on this