Updated spec to new version 5.6.0
Revert "Updated spec to new version 5.6.0"

This reverts commit 5e69523ebadc8a85353748783d7264157e43ba75.
Updated RevMobSDK.podspec to new version 5.6.0
Merge pull request #1859 from evil159/master

Updated RevMobSDK to 5.6.0 version