Added: dot config files
Added: Rakefile
Fixed: bootstrap task

When the target file of symlink had already exist, task failed.
Now skip the symlink creation if it exists.
Added: alias.diffw diff with color-word
[GIT] Enabled: rerere
[GIT] Added: attribute file
[GIT] use exiftool to diff png
Added: README
[GIT] Added: alias.sst, status --short
[PRY] Added: .pryrc file