Fixed #117 -- Added support for EdgeNgram and Ngram.

Docstring has been updated

tests has been created

some corrects of unusable imports

Fixes created after notices in pull request.

class of mock has been fixed, test of indexation edge ngram has been created

big cycle has been separated to generator

fix depencies

tests has been updated

some refactoring and generator of edge ngram terms has been updated

Package "six" has been removed from requirements, class with edge ngram
field has been created. Edge ngram field has been removed from another
mocks. Indexation for this class has been splitted to separate class.

unimportant tests has been removed

both techniques, ngram and edge ngram, has been implemeted

little refactoring

some minor fixes