Allow global install and use external modules

[cebe]

currently it is not possible to install uipf on a system with make install and also other modules which are not directly located in uipf development directory can not be used. This pull request adds some changes to improve the situation. It is work in progress and should not be merged.

• [x] Add install targets ot CMakeLists.txt
• [x] Change ModuleManager to be able to load modules from different locations

• [ ] open bug (opencv waitkey does not work in console module):

  uipf: symbol lookup error: /Code/build/libVisualizationModule.so: undefined symbol: _ZN2cv7waitKeyEi

• [x] fix chdir() issue for console too (to make relative paths in yaml files work)
• [x] Add Documentation on how to load modules
• [x] Add Documentation on how to compile external modules

[akarsh]

Is the issue OS environment specific or library dependency or file path miss match specific in a brief overview ? I can test on Mac OS if you want to have overview.
As, i installed opencv library with XCODE & I have a small test with cmakelists successful to check for blurrying an image through console arguments.

cmake_minimum_required(VERSION 2.8)
project( BlurImage )
find_package( OpenCV )
include_directories( ${OpenCV_INCLUDE_DIRS} )
add_executable( BlurImage BlurImage.cpp )
target_link_libraries( BlurImage ${OpenCV_LIBS} )

[cebe]

these changes might fix the issue described in #114 so you might try to install on mac again. however the make install command may not install it to the correct directories as I do not know where to best store things on mac. But maybe CMake already handles this correctly...