Revert "Add -Wno-deprecated to clang++ too, for travis-ci."

This reverts commit b67941526159b778bfb632054ed07c93c05f58b5.
Revert "Add the Ubuntu specific path for FindOGRE.cmake to CMAKE_MODULE_PATH."

This reverts commit 0d836e0f4bd96f7fb4966a39bc37a4fa9c35c7a5.
Revert "Install libois-dev on travis-ci VMs before building the project."

This reverts commit 5335c60babd3cd3f16288337c64eefffb88b4450.
Revert "Search for libogre-dev in the official Ubuntu Precise repositories."

This reverts commit 29f62eb30979a39e51175fd3b3e836030deddbbb.
Revert "Automatically answer with "yes" to all add-apt-repository queries."

This reverts commit 60257743fde6e9cfad5858ff22fc845f4eeeaadd.
Revert "Remove invalid -qq argument from apt-add-repository."

This reverts commit be60971a6a7dceb465dd8051fe86ffebe9f80549.
Revert "Install OGRE on travis-ci Ubuntu VMs before building the project."

This reverts commit b347408407d4b5d8c5e1f682c34adecd71be72cd.