Notebook Example - CNN for Text Classification (#413)

* adding textcnn example

* updated example

* Working example on IMDB dataset

* updated .gitignore

* Added text cnn example

* Delete .gitignore

* removed .ipynb_checkpoints

* Updated notebook per comments

* moved notebook

* Added more information on TEXT, LABEL, description of problem

* added better description of iterators

* Updated notebook with less overfitting, and fixed text

Author: anmolsjoshi