Update to v1.5.2.0

Quick update to prevent Dropbox upgrading to version 1.6.13.
Additionally, the changelog was removed from the readme files and put in an own file called “changelog.txt” and a Dutch readme file was added (thanks to Sam Bouwer).

Update to v1.5.1.0

Just a quick update to fix the automatic update of Dropbox to version 1.6.11.

Changelog:
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1.5.1.0 (02.01.2013):
#Dropbox update prevention for 1.6.11
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