Removed JAR files that are no longer used.

Removed the server contrib folder since it is outdated and no longer needed.
Issue: MIRTH-3086
Added a 'thirdparty' folder to the 'docs' folder in the Server. The folder contains THIRD-PARTY-README.txt which has license information for third party software/libraries that are included in Mirth Connect.

Added several license files that are referred to in THIRD-PARTY-README.txt.

Added third party acknowledgements to the About dialog in the Administrator in order to comply with the license terms of various third party software.

The majority of included third party software/content is covered in this commit, but there remains a handful that still needs proper attribution.
Issue: MIRTH-2958
Fixed MigratableConverter failing if the class it was migrating does not have a no argument constructor. Now we are using the reflection provider from XStream to create the instance of the class. As long as XStream is running in enhanced mode (which by default it is unless the JVM does not support it), it will still instantiate the class. Sun14ReflectionProvider is what we are expecting will be retrieved from XStream.

ListenerConnectorProperties now implements Migratable

Removed the implementation of migrate3_0_1 from the abstract classes ConnectorProperties, DataTypeProperties, and DataTypePropertiesGroups.
Each child class of the aforementioned classes must now implement their own migration methods.
Issue: MIRTH-3076
Removed the following directories from trunk (none were included in builds):
ant - no longer kept up to date with current versions
itext - a modified version of itext with bug fixes that is no longer used
launchers - windows launchers that are no longer used
uima - not updated for 3.0, but remains in the 2.x tags and branches