Specify Swift range version from 4.2-5

Update documentation

Merge pull request #210 from layoutBox/fix_podspec_for_swift_5.1.1

Update the podspec to support all Swift versions

Update podspec to specify explicitly supported swift versions: ['4.2'…

…, '5.0', '5.1']

Update version to 1.8.11

Update to version 1.8.10

Update version to 1.8.9

Update for Release 1.8.8.

Update changelog.md

Update version to 1.8.6