The meta-oe provides since commit 8700ba38@openembedded/meta-openembedded
(commit date: 2016-01-14) [1] a recipe for the POCO C++ Library.
Consequently, this commit removes the libpoco recipe in the
meta-ros layer.

As meta-ros already depends on the meta-oe layer, the poco
recipe is available in release version since 2016-01-14,
and the poco recipe in meta-ros is redundant for these versions.
However, this commit still provides the currently latest poco
recipe [2] for users that are not using a recent version of the
meta-oe layer.

[1] http://cgit.openembedded.org/meta-openembedded/commit?id=8700ba38804af3c27f3662737f679afa1bdc86da
[2] http://cgit.openembedded.org/meta-openembedded/tree/meta-oe/recipes-support/poco?id=0a2bd4f9784253a8a8dda35e3c4dbd75931d3564



Signed-off-by: Lukas Bulwahn <lukas.bulwahn@oss.bmw-carit.de>

The recent versions of the rosbridge_library package does not depend
on python-pytz anymore. So, this commit removes the dependency in
the recipe file and removes the now unneeded python-pytz recipe.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@oss.bmw-carit.de>

Bitbake gives a dependency error when IMAGE_FEATURES += " dev-pkgs" is set.

This is because the urdfdom-headers package contains headers only, as a
result bitbake packages them into urdfdom-headers-dev and leaves
urdfdom-headers empty.

Since there are no files to be packaged into urdfdom-headers bitbake
doesn't create the package. urdfdom-headers is a dependency
of urdfdom-headers-dev by default so bitbake errors when building an image
with dev-pkgs enabled.

ALLOW_EMPTY tells bitbake to create a package even when nothing is in it.
This resolves the dependency issue of urdfdom-headers-dev
http://www.embeddedlinux.org.cn/OEManual/recipes_packages.html

While testing the version updates, I noticed that the
camera-calibration-parsers were missing the roscpp dependencies,
and hence do_configure failed with:

```
|   Could not find a package configuration file provided by "roscpp" with any
|   of the following names:
|
|     roscppConfig.cmake
|     roscpp-config.cmake
|
|   Add the installation prefix of "roscpp" to CMAKE_PREFIX_PATH or set
|   "roscpp_DIR" to a directory containing one of the above files.  If "roscpp"
|   provides a separate development package or SDK, be sure it has been
|   installed.
| Call Stack (most recent call first):
|   CMakeLists.txt:4 (find_package)
|
|
| -- Configuring incomplete, errors occurred!
```

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@oss.bmw-carit.de>