Image Normalization added

refer #503
Here are some example of how this is diff from equalize n stretch:

Original Image=

![wom](https://f.cloud.github.com/assets/1975189/450111/1e4dcf64-b288-11e2-8d0c-08b2c7b250d0.png)

Normalized image acc to my function:

![my_normalized](https://f.cloud.github.com/assets/1975189/450110/1e4b8d94-b288-11e2-8bc9-e03d9fffbe58.png)

Result of the equalize function:

![histeq](https://f.cloud.github.com/assets/1975189/450145/67b88d1e-b289-11e2-9379-65997759c3b1.png)

Result of stretch function(using the default parameters, no other parameters could match the result of the new normalized function as both are completely different functions):

![stretch](https://f.cloud.github.com/assets/1975189/450148/73aa8afa-b289-11e2-9b6c-d7ed2045da79.png)