Bond Version 6.10.3 Updates ReactiveKit to 3.10, which is only Swift 5 Compatible

[reaganwood1]

Reactive Kit got updated a few days ago to version 3.10. Bond Version 6.10.3 began pulling that version of the library, even though it's only compatible with Swift 5.

Workaround, I had to manual go into the cocoa pods .podsec file and set the Reactive Kit version and checksum to a version below Reactive Kit 3.10 to avoid build errors, since we have not upgraded to Swift 5 yet.

Minor version bump should not contain breaking changes as Reactive Kit 3.10 contains breaking changes for bond version 6.10.3.

[chickdan]

#213