Improve documentation and tests

[zenangst]

This PR aims to slightly improve tests and the source code documentation.

It also resolves a Segfault that seems to have surfaced with Swift 3.0.1

1.	While type-checking 'observeValue' at Spots/Sources/iOS/Classes/SpotsScrollView.swift:115:17
2.	While type-checking expression at [Spots/Sources/iOS/Classes/SpotsScrollView.swift:127:19 - line:128:57] RangeText="keyPath == #keyPath(contentOffset)
          && (isDragging == false && isTracking == false)"

This seems to be resolved by guarding for keyPath and reversing the compare statement.

[vadymmarkov]

@zenangst I see a lot of public in this PR 😄 Why is that?

[zenangst]

The damn linter is complaint about comments on internal implementations.
Also some of the things probably should be public to being with ;)

[vadymmarkov]

I would limit the amount of open and public to simplify the public API, so in the end there are only functionality that should be accessible. But if it's supposed to be public, then we're good here.

[vadymmarkov]

I see tests are failing 😄

[zenangst]

@vadymmarkov only on the damn PR... TRAVIS!!! 🔨

[zenangst]

And now the tests pass 🚦

[zenangst]

This will improve both #279 #290

[codecov-io]

Current coverage is 69.99% (diff: 84.84%)

No coverage report found for master at 03c2eb0.

Powered by Codecov. Last update 03c2eb0...57e173f