[Partial fix for #1372]Added SimpleTypesExcludeFilter to exlcude validat...

...ion on simple types and also added tests to cover scenarios.

@yishaigalatzer @pranavkm @rynowak @harshgMSFT 

Note:
- This PR does not have comments. I will add them once we agree upon the changes.
I understand that. But, based on the discussion with @pranavkm, 
1. I think that we don't have the defined set of "simple type' cross platforms, and it could have different meanings for the different applications.
2. I'm not sure if ModelBinding is the good place for the TypeHelper class. 
3. There are two different internal TypeHelper class in Mvc.Core and Mvc.Modelbinding. 

I agree with you, but I think we should file a separate bug to combine those type helpers that we can use cross platform...