add TreeWriter.java
fix TreeWriter
use TreeWriter to write Trees and Blobs Structure.
Merge branch 'add-tree-writer' into change-parser-output
add TextFormatTreeWriter
added writeBlob mehtod.
Add 'Start' and 'End' lines to Tree represents.
[bug fix] supreessed output of 'Start' and 'End' line when tree is root.
changed order of output text.
Extract createTreeMap Method
Extract createBlobMap Method.
[bug fix] create parent directory of outputFile when it doesn't exist.
[bug fix] add default constructor to the TreeWriter
Merge branch 'add-text-format-tree-writer' into change-parser-output
change writer to TextFormatTreeWriter
added FileFormatTreeWriter
copy implementation from TreeWriter
change TreeWriter from class to interface
removed baseDir from FileFormatTreeWriter
rename method parameter