Fix renaming of mkbranch to make-branch.

[adiroiban]

Problem

It looks like mkbranch script was renamed to make-branch but there was no update in setup.py and readme

Running pip install -e . will get something like

    Adding twisted-dev-tools 0.0.2 to easy-install.pth file
    Installing force-build script to /home/adi/chevah/twisted/build/bin
    error: [Errno 2] No such file or directory: '/home/adi/chevah/twisted-dev-tools/bin/mkbranch'

Why we got this

Nobody bother to see if master can still be installed.

Changes

Update setup.py and readme

How to test

In a virtualenv, run pip install -e /path/to/you/dev-tools/clone You should see that package is successfully installed.

Please let me know if I did something wrong :) Thanks!

[thijstriemstra]

This is a duplicate of #4

[glyph]

It is indeed a duplicate of #4.