Remove need of saving images before logging.

[toshal-a]

While logging armadillo matrices as Images for visualization in mlboard currently it is mandatory to save armadillo matrices as an image temporarily before logging. The reason we do that is to get the armadillo matrices in encoded format in the form of binary string. However, due to this, it needs quite a lot of reading and writing to the file system which can be avoided. It might also lead to increased time while logging thousands of images.
So the best solution to tackle this issue is to remove the need of saving images. This issue might need a good understanding of the Image support code. For more info on the topic you can see the following comment.
#6 (comment)