Fixed README.txt

Fixed README.txt.

Bumped version to 0.7.3.

Bumped version to 0.6.16.

Using django-lfstheme 0.7.2

Added tag 0.6.15 for changeset de9e39fcc571

Added tag Added, documentation, for, Price, Calculation, field for ch…

…angeset 9c017a036aa7

Added tag 0.6.14 for changeset eda7a8910192

Updated README.txt

Added tag 0.6.13 for changeset 08fc60fae6e2