(add) Feature for storing not only 'numpy arrays' but also file format required for training and refactoring examples folder

[graykode]

PR for #7 commits for refactoring example folder

• https://github.com/graykode/matorage/pull/8/commits/dd4ffb01426883259c7d12effa39a606e98cb695
• https://github.com/graykode/matorage/pull/8/commits/9da273bc485320ba5541896ba5b9cff38589b62f
• https://github.com/graykode/matorage/pull/8/commits/583624474476dd10af9c805a85049a6161545873

commits for splitting examples and benchmark

• https://github.com/graykode/matorage/pull/8/commits/e43842dc07137479e3236db1db7161e75c5c794c

commits for renaming a function

• https://github.com/graykode/matorage/pull/8/commits/256033356336e5e1dfc71e7d9b124554e6716727

commits for adding filetype dataset

• https://github.com/graykode/matorage/pull/8/commits/b666e28d3ad2351920f830fcccf0c66a648be241
• https://github.com/graykode/matorage/pull/8/commits/ae7979a45f39acf4baf779453a19a2e8a345f16c
• https://github.com/graykode/matorage/pull/8/commits/aeb3e302b483f0621cd1fe75d390d5576ad6a200
• https://github.com/graykode/matorage/pull/8/commits/f5fcaaae24203918fa27d1f6cff78da4490fb611