fixing 'dewPoInt64' typo
adding precipProbability DataMember

From API docs:

precipProbability: A numerical value between 0 and 1 (inclusive) representing the probability of precipitation occuring at the given time. (If precipIntensity is zero, then this property would be redundant and will therefore not be defined.)
removing '64' from dewpoint DataMember

According to the docs:

dewPoint: A numerical value representing the dew point at the given time in degrees Fahrenheit.
Merge pull request #1 from Ryan-Anderson/master

Data-Contract Bug Fixes and Updates