Add masking interface, filtering kernel, and an example of filtering use

[gprabowski]

We have created an implementation of high speed raw data filtering algorithm and this accommodation allows meta-json-parser to use this filtering stage in a plug-in fashion (plugging it as example in meta_cudf.cu:254)

This probably won't be the final version, but provides a filtering interface for python binding created

[gprabowski]

In the newest commit I added filtering interface use. @abstrackt will soon provide a repo with instruction on how to generate a filtering cascade, which is placed in the cascade.hpp config file. This completes all changes that were to be made during the fitering project.

[abstrackt]

Cascade generation tool is available at https://github.com/abstrackt/cascade-generation, see README for usage instructions.