Add ilike helper method

[abanoub-fathy]

Summary

Add ILIKE helper method for make it easy to filter by ILIKE condition

So instead of writing this

builder.Where( "username ILIKE " + builder.Var("%"+User.Name+"%"))

we will use this

  builder.Where(builder.ILike("username", "%"+User.Name+"%"))

[huandu]

Thanks for your contribution. Your PR works great!

[coveralls]

coverage: 96.274% (+0.009%) from 96.265%
when pulling 4b8a96c on abanoub-fathy:add-ILIKE-helper-method
into 9fc30d9 on huandu:master.