added test
created core logic.
added templates
supported epub, from markdown
added converter.
refactoring
specified path and copy exe.
modified gitignore.
authorをクラスに
#6 "で囲って直した
fixed test data.
#1 If the book has coverImageBase64, an ePub book is exported with a specified cover image.
closed #1.
Supported the mobi format.
Merge pull request #7 from mono0926/feature/#1CoverImage

Feature/#1 cover image