Update SqlMapper.cs

- code improvements

fix Cast at QueryAsync<T>

fixed the "UdtTypeName property must be set for UDT parameters" error.
C#  :  .net Framework 4.5.1
Sql server 2012

Little changes :)

Correct the spelling mistake, and change the variable name to satisfy the naming conventions.

This also brings the failing test count down to 1: only
TestCustomParameters fails.

Runtime dependency

SqlMapper global/default CommandTimeout

remove commented json so dnx tooling doesn't break

Language correction on Readme

Fix capitalization in README

breakage in latest dnx builds (beta6 nightlies)

Tweak to readme.

Update Contrib README with small nuance about Delete

Deleting an entity will delete only by a specified key property and not by
any specified parameter

Removed text about connections having to be open, which is not true any longer.

Adding section about SQLite limitation

More information at #300

Better Dapper.Contrib README

- Added an example for the [Table] attribute which was missing.
- Additionally separated things onto separate lines for better
readablility
- Better headings

Brackets around property names in Update & Delete

Modified Update & Delete method to be consistent with Insert by adding brackets around property names