Resolve "timit dataset not complete"

Closes #8

See merge request fast/speechdatasets.jl!7

fixed cmudict path creationg

See merge request fast/speechdatasets.jl!6

Fix channels

See merge request fast/speechdatasets.jl!5

Resolve "prepare lexicon"

See merge request fast/speechdatasets.jl!4

Dataset

See merge request fast/speechcorpora.jl!3

Support multi channel supervisions

See merge request fast/speechcorpora.jl!2

Timit data preparation

See merge request fast/speechcorpora.jl!1