COMP: Fix build against Qt < 4.8

Add a fallback for QProcessEnvironment::keys(), which was added in Qt
4.8.
Merge pull request #47 from mwoehlke-kitware/fix-build-with-older-qt

Fix build against Qt < 4.8
BUG: Fix unit tests single/multi-configuration

Fix incorrect handling of single- versus multi-configuration generators
assuming that we are multi-configuration iff WIN32. Fix missing handling
of multi-configuration generators in recently added configure launcher
tests.
BUG: Fix App4ConfigureLauncherTest-ConfigureStep

Tweak ctkAppLauncher.cmake to accept an optional argument with build
configurations to use as hints when looking for the launcher executable
(which is needed to find it in the build dirextory of a multi-config
build). Adjust test invocation to pass along current configuration to
the test scripts, and aforementioned test to pass along the
configuration when configuring the test project, for use in the new
search path list.

This fixes App4ConfigureLauncherTest-ConfigureStep failing with
multi-config generators.
BUG: Fix TestLauncherVerbose test

Fix regex used in TestLauncherVerbose looking for "LD_LIBRARY_PATH",
which is not present on OS/X or Windows, to look for the appropriate
variable. (We're a little lax; we'll take either "LD_LIBRARY_PATH" or
"DYLD_LIBRARY_PATH" on not-Windows. On Windows, we'll look for "PATH".
This should be close enough given we're really looking for logging in
general and not so much specific logging messages except as that's the
easiest way to check for logging output.)
Merge pull request #49 from mwoehlke-kitware/fix-verbose-test

Fix TestLauncherVerbose test

Tested on Ubuntu 13.10 on Debug build
```
100% tests passed, 0 tests failed out of 53
```
Merge pull request #48 from mwoehlke-kitware/test-config-fixes

Test config fixes