Update / Remove CHANGELOG

[jonny-improbable]

Hi @nathanboktae, thanks for your contributions to this very useful library.

The CHANGELOG file appears to have not been updated since release 3.5 and there are no entries for the newer 4.x releases (I'm am currently trying to see what changes from 4.0 -> 4.1 may impact our project).

Thanks!

[nathanboktae]

Yeah I'm not sure if @metaskills had some totally automated process for it, but I should figure out one (it might not be in the same format), but here's git log --oneline --decorate:

cfd02ef (HEAD -> master, tag: v4.1.0, origin/master, origin/HEAD) Release 4.1.0
ebd42f1 Merge pull request #237 from francetv/master
424dd4a Put back original error codes
bce6960 Don't use process.exit, but set exit code
46cbb35 Merge pull request #232 from astorije/patch-2
599953b Use SVG version of the Travis CI badge
ba4b66c Merge pull request #229 from erikvold/package-desc-edit
b907296 Edit package.json nocha -> mocha
6d8d25c Shorten and simplify the reporter README section. Fixes #208.
ad77952 (tag: v4.0.2) Don't block usage of xunit with file since it has been fixed (mochajs/mocha #2005)
39996c1 Add a test for the phantomjs bug in 1.9.8 described in #167 and ariya/phantomjs #12697
22efbb6 (tag: v4.0.1) Version 4.0.1
a148039 Merge pull request #205 from kaelzhang/master
dcbaafe Uses require.resolve to get the realpath of mocha-phantomjs-core.js, fixes #204
9fed801 (tag: v4.0.0) Merge v4 into master