Update README.rst
Update README.rst

* Remove Bitdeli badge as service shat down
* Add link to Exempi project page
* Use shields.io for Travis-CI, Coveralls and Pip version badges
* Remove pip download badges as PyPI is not providing these statistics anymore
* Change link to pypid.in to pypi.org as pypid.in is dead
* Add badge for readthedocs documentation
* Fix typos
* Fix issue with too short Documentation underline causing PyPI rST renderer to
  display ugly plain text

python-xmp-toolkit/python-xmp-toolkit,python-xmp-toolkit/python-xmp-toolkit