[TASK] Update minimum TYPO3 version to 6.2

This is needed for moving the TCA code from ext_tables.php to Configuration/TCA/Overrides.
[TASK] Move tt_content TCA overrides to separate file in Configuration/TCA/Overrides

To allow for better caching, TCA customizations should be done in Configuration/TCA/Overrides and not ext_tables.php anymore (since Typo3 core version 6.2). This change also allows for compatibility with extensions that have already embraced this new way, their modifications would potentially get lost otherwise.
Merge pull request #120 from pkerling/tcafix

Move tt_content TCA overrides to separate file in Configuration/TCA/Overrides