Fix top level dir

[kevinj-z]

• When the cookiecutter project template directory name matches a
  sub-directory name, battenberg will fail to install or upgrade to a
  collision in shutil.move.
• Rather than moving the project files up a directory, use a separate
  temporary directory as a staging ground for the cookiecutter output.
  Then move the desired contents into the temporary worktree.

[codecov-commenter]

Codecov Report

Merging #15 into master will increase coverage by 0.38%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #15      +/-   ##
==========================================
+ Coverage   95.89%   96.27%   +0.38%     
==========================================
  Files           6        6              
  Lines         219      215       -4     
==========================================
- Hits          210      207       -3     
+ Misses          9        8       -1     

Impacted Files	Coverage Δ
battenberg/cli.py	91.11% <100.00%> (ø)
battenberg/core.py	96.70% <100.00%> (+0.91%)	⬆️

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[alexlatchford]

Would you mind updating the HISTORY.md file with the details of the change, guessing this fix is backwards compatible so just a patch release version bump should be fine.

[kevinj-z]

bumped to 0.2.3 in HISTORY.md. from all of my testing, the change is backwards compatible.

[alexlatchford]

Looks good just tested it out on one of our projects and didn't break! Thanks for the contribution. Ping me on Slack when you've merged this and I can git tag and publish a new version for you :)