[seaf-cli] Add 'create' command to create a library

This commit adds a new command called 'create' so that we can use this
command to create a new library.
Made readme more clear, fixed a couple grammar issues
Merge pull request #414 from etjossem/patch-1

Made readme more clear, fixed a couple grammar issues
More and better de_DE Translations
Merge pull request #416 from allo-/master

More and better de_DE Translations
Fix FILE leak if an error happens while writing pidfile.

Call fclose() even if writing to the PID file failed, otherwise it was simply leaked in this case.
Merge pull request #426 from vadz/patch-1

Fix FILE leak if an error happens while writing pidfile.
Remove dependence on json-glib, use jansson instead.
Fix a compile error.
[win] Fix task cancel bug in data transfer.
upgrade source/msi/deb version
update buil-msi.py to include qt translation files
remove gui/ and web/
remove po/
fixed "make dist" after remove po/
Modify README
Update README.markdown
Merge pull request #442 from etjossem/patch-1

Update README.markdown
Fixed typos and improved English grammar a bit
Merge pull request #446 from hanswolff/patch-1

Fixed typos and improved English grammar a bit