* Issue #958: Travis CI should enfore clang-format standards

This patch adds clang format support to the travis bots.

* Update path

* Roll back to version 8 since 9 is in test

* Cleanup clang

* Revert "Delete JSONCPP_DEPRECATED, use [[deprecated]] instead. (#978)" (#1029)

This reverts commit b27c83f6.

This option personally drives me crazy. I think it's much more readable
to be able to see one parameter per line when there are many.

    clang-format -style=llvm -dump-config > .clang-format