rospack: improving runtime dependencies (resolves #116)

This commit includes further changes to build rospack-native.
libpoco: openssl required for libpoco when compiling pcl-ros

When compiling pcl-ros, bitbake aborts because for compiling the
Crypto library in libpoco, it needs the openssl headers.

The condensed error output is

** Compiling src/CipherKeyImpl.cpp (debug, shared)
arm-oe-linux-gnueabi-g++  -march=armv5te -marm -mthumb-interwork
-Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed
--sysroot=/home/lukas/oe-core/build/tmp-eglibc/sysroots/qemuarm
-I ... -DPOCO_BUILD_HOST=host -DPOCO_NO_WSTRING -DPOCO_UNBUNDLED
-D_XOPEN_SOURCE=500 -D_BSD_SOURCE -D_REENTRANT -D_THREAD_SAFE
-DPOCO_NO_FPENVIRONMENT  -g -D_DEBUG -fPIC -c src/CipherKeyImpl.cpp
-o ...
In file included from include/Poco/Crypto/CipherKeyImpl.h:44:0,
                 from include/Poco/Crypto/CipherKey.h:44,
                 from src/CipherKey.cpp:37:
include/Poco/Crypto/OpenSSLInitializer.h:45:33: fatal error: openssl/opensslconf.h: No such file or directory
 #include <openssl/opensslconf.h>
                                 ^
compilation terminated.
In file included from include/Poco/Crypto/CipherKeyImpl.h:44:0,
                 from src/CipherKeyImpl.cpp:37:
include/Poco/Crypto/OpenSSLInitializer.h:45:33: fatal error: openssl/opensslconf.h: No such file or directory
 #include <openssl/opensslconf.h>
                                 ^
compilation terminated.
make[1]: *** [.../tmp-eglibc/work/armv5te-oe-linux-gnueabi/libpoco/1.4.6p1-r0/poco-1.4.6p1-all/Crypto/obj/Linux/armv5te/debug_shared/CipherKey.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make -C /home/lukas/oe-core/build/tmp-eglibc/work/armv5te-oe-linux-gnueabi/libpoco/1.4.6p1-r0/poco-1.4.6p1-all/Util
make[1]: *** [.../tmp-eglibc/work/armv5te-oe-linux-gnueabi/libpoco/1.4.6p1-r0/poco-1.4.6p1-all/Crypto/obj/Linux/armv5te/debug_shared/CipherKeyImpl.o] Error 1
make[1]: Entering directory `/home/lukas/oe-core/build/tmp-eglibc/work/armv5te-oe-linux-gnueabi/libpoco/1.4.6p1-r0/poco-1.4.6p1-all/Util'
cleaning up recipes-devtools/python recipes
catkin class includes BBCLASSEXTENDS
roscpp-core: collected common definition in .inc file
ros: removing superfluous definitions
images: cleaned and renamed image recipe
tuning newlines
initial ros-tutorials and common-tutorials recipes (resolves #124)
README: was updated to hydro; core-image was renamed
CONTENTS: adjusted to current state and tuned formatting

This commit renames file CONTENT to CONTENTS, reflecting its
intended meaning. For the difference between the two words, see
http://english.stackexchange.com/questions/13556/content-or-contents
Merge pull request #140 from bulwahn/master

Minor improvement, some cleanup and provide tutorials