Removed duplicate podspec file and updated the root podspec file.

Fixed a bug in the explicit constraint method. Fixed unit tests on io…

…s and tvos. Moved tvos swift version to 4.0.

Fixed a bug in the explicit constraint method. Fixed unit tests on io…

…s and tvos. Moved tvos swift version to 4.0.

Bumped version number.

Update README.md

Added module name to podspec

bumped podspec

Updated visibility of constant constraint function and updated podspec

Bumped podspec version