More customization options, bug fixes, and future compatibility.

[shadow-of-arman]

1. Changed the arrowLabel to arrowImageView, so it can be changed by whom ever is using this framework. added a default arrow for the framework that is less pointy than >.
2. Added a color value for the arrow so devs can change the color of the arrow easier, no matter what icon they are using.
3. Added a section background color value so devs can change the background color of the collapsable section.
4. Added an alignment value that changes the alignment of the section label AND changes the position of the arrow depending on left or right, so this framework can support languages like Persian or Arabic since they are right to left aligned.
5. Changed how the animation for the arrow rotating was written, (used CGAffineTransform) which resulted in a smoother animation and removed the bug that displayed no animation when rotating back up. (collapsed)
6. Removed a bug that would reset the arrow to collapsed mode even though the section was still open. (this occurred when an open section would get redrawn when going outside the visible view)
7. Resolved every single warning that happened when setting the minimum deployment target above iOS 11, removed deprecated code if iOS version meets the requirement, and changed the swift version to swift 5.
8. Updated travis.yml to test on newer iOS versions on a newer Xcode version.

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@86645bc). Click here to learn what that means.
The diff coverage is 79.16%.

@@            Coverage Diff            @@
##             master      #69   +/-   ##
=========================================
  Coverage          ?   86.98%           
=========================================
  Files             ?        2           
  Lines             ?      146           
  Branches          ?        0           
=========================================
  Hits              ?      127           
  Misses            ?       19           
  Partials          ?        0           

Impacted Files	Coverage Δ
...roller/CollapsibleTableSectionViewController.swift	91.02% <76.47%> (ø)
...ionViewController/CollapsibleTableViewHeader.swift	82.35% <80.64%> (ø)

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