Separate format1 and format2 documentation.

The main how-to index is for format2. It refers format1 users to a subdirectory.
The format2 version recommends <depend>, but does not yet mention <devel_depend>
or <exec_depend>.
The format1 version does not mention <depend>.
 remove empty format1 test pages
add rostest configuration page (#437)
add how-to page on downloading test data (#437)
Remove spare parenthesis in documentation.

I tried to copy and paste the example, and it failed. Fixed.
add gtest page (#437)
add python unit test page (#437)
format1 (only) version of the how-to docs
Merge pull request #443 from jack-oquin/format1

Format 1 (only) version of how-to documentation
fix generating pkg-config files with empty -I directives (fix #445)
add prefix to generated pkg-config files (fix #444)
fix prefix in pkg-config files (regression of last commit, #444)
fix catkin_prepare release if git repo has multiple remotes (fix #450)
modify catkin_prepare_release to not change the remote repo by default, add option --push for old behavior (fix #451)
add options to configure without tests
update check in generated pkgConfig.cmake files to work independent of cmake policy CMD0012 (#452)
add dummy target to catkin_EXPORTED_TARGETS if empty (fix #453)
fix registered ctest command to return error code when tests are failing
Add the --from-pkg option to catkin_make_isolated

This is mutually exclusive with --pkg and takes
a single package which all packages leading up to
it are skipped, it is built and then the process
continues as normal.
Merge pull request #454 from ros/add_from_pkg

Add the --from-pkg option to catkin_make_isolated