ConcurrencyTaglet with curly brackets

This is an adaptation to more strict behaviour of the JavaDoc-Tool of Java-8 and replace the angular brackets in some text placeholders by curly brackets, see also issue #1.

First release

Contains 3 taglets:

• @doclets.concurrency
• @doclets.experimental
• @doclets.spec

A specialized doclet is available, too. It helps to exclude any program element from public API using the tag @doctags.exclude

This initial version runs under Java-6 and Java-7.