DOC move images under lessons/swc-shell/ -> img/lessons/swc-shell/

	renamed:    lessons/swc-shell/absolute_path.png -> img/lessons/swc-shell/absolute_path.png
	renamed:    lessons/swc-shell/absolute_relative_path.png -> img/lessons/swc-shell/absolute_relative_path.png
	renamed:    lessons/swc-shell/command_shell.svg -> img/lessons/swc-shell/command_shell.svg
	renamed:    lessons/swc-shell/decwriter.jpg -> img/lessons/swc-shell/decwriter.jpg
	renamed:    lessons/swc-shell/direct_shell_usage.png -> img/lessons/swc-shell/direct_shell_usage.png
	renamed:    lessons/swc-shell/filedir_challenge.png -> img/lessons/swc-shell/filedir_challenge.png
	renamed:    lessons/swc-shell/filesystem.png -> img/lessons/swc-shell/filesystem.png
	renamed:    lessons/swc-shell/find_file_tree.png -> img/lessons/swc-shell/find_file_tree.png
	renamed:    lessons/swc-shell/google_vs_grep.png -> img/lessons/swc-shell/google_vs_grep.png
	renamed:    lessons/swc-shell/home_directories.png -> img/lessons/swc-shell/home_directories.png
	renamed:    lessons/swc-shell/nano.png -> img/lessons/swc-shell/nano.png
	renamed:    lessons/swc-shell/nano_quotation.png -> img/lessons/swc-shell/nano_quotation.png
	renamed:    lessons/swc-shell/permissions_table.png -> img/lessons/swc-shell/permissions_table.png
	renamed:    lessons/swc-shell/process_stdin_stdout.png -> img/lessons/swc-shell/process_stdin_stdout.png
	renamed:    lessons/swc-shell/public_private_keys.png -> img/lessons/swc-shell/public_private_keys.png
	renamed:    lessons/swc-shell/relative_path.png -> img/lessons/swc-shell/relative_path.png
	renamed:    lessons/swc-shell/remote_shell_usage.png -> img/lessons/swc-shell/remote_shell_usage.png
	renamed:    lessons/swc-shell/running_a_process.png -> img/lessons/swc-shell/running_a_process.png
	renamed:    lessons/swc-shell/running_wc.png -> img/lessons/swc-shell/running_wc.png
	renamed:    lessons/swc-shell/running_wc_sort.png -> img/lessons/swc-shell/running_wc_sort.png
	renamed:    lessons/swc-shell/running_wc_sort_head.png -> img/lessons/swc-shell/running_wc_sort_head.png
	renamed:    lessons/swc-shell/shell_as_process.png -> img/lessons/swc-shell/shell_as_process.png
	renamed:    lessons/swc-shell/shell_on_shell.png -> img/lessons/swc-shell/shell_on_shell.png
	renamed:    lessons/swc-shell/vlad_homedir.png -> img/lessons/swc-shell/vlad_homedir.png
	renamed:    lessons/swc-shell/x_for_directories.png -> img/lessons/swc-shell/x_for_directories.png
DOC fix swc-lesson images' path after mv images to img\lessons\swc-shell

	modified:   _includes/guide-shell/create/lesson.html
	modified:   _includes/guide-shell/filedir/challenges.html
	modified:   _includes/guide-shell/filedir/lesson.html
	modified:   _includes/guide-shell/find/lesson.html
	modified:   _includes/guide-shell/intro/lesson.html
	modified:   _includes/guide-shell/pipefilter/lesson.html
DOC base on #81, copy swc-shell images for ipynb

	new file:   lessons/swc-shell/files/absolute_relative_path.png
	new file:   lessons/swc-shell/files/filesystem.png
	new file:   lessons/swc-shell/files/home_directories.png
	new file:   lessons/swc-shell/files/vlad_homedir.png
Merge pull request #100 from HaveF/reorg_images

PR: Reorganize images