Added the ability to delete keys to WriteStream.
Moved the type parameter from the WriteStream's options to the object.
Fixed unwanted README change.
Changed " into '.
Added the 'type' option to  createWriteStream.
Removed useless branching in write-stream.
Added in the README the new constructor option for createWriteStream.
Removed duplicted test.
Added a test for covering the wrong type behavior in WriteStream.
Removing useless variables in WriteStream