fix a bug in DateRow with countdown timer

fixes #188
Merge branch 'master' of https://github.com/clayallsopp/formotion
Remove nil values before saving the form

fixes #189
don't override row#value if there was not a previously rendered value

fixes a problem when subforms get added to a persisted form after the first persistence

thats a mouthful
add a subform to the Persistence example
show spaces in iOS7. fixes #169
Strip out whitespace on iOS7

if this causes headaches for you, let me know
account for how Form#render & display_key works w/ persistence. fixes #190