Removed pull request numbers from commit messages

refs https://github.com/TryGhost/Toolbox/issues/276

- this removes the PR numbers from commit messages that we prepate for
  the changelog
- removing it prevents us needing to fix the path to the PR if the
  commit was done in a different repo

ghost/release-utils/lib/changelog.js

@@ -27,7 +27,7 @@ class Changelog {
         }
 
         const commands = [
-            `git log --no-merges --pretty=tformat:'%at * [%h](${options.githubRepoPath}/commit/%h) %s - %an' ${options.lastVersion}.. ${sign} ${this.changelogPath}`
+            `git log --no-merges --pretty=tformat:'%at * [%h](${options.githubRepoPath}/commit/%h) %s - %an' ${options.lastVersion}.. | sed 's/(#[0-9]{1,})//g' ${sign} ${this.changelogPath}`
         ];
 
         _.each(commands, (command) => {