Debianize

Add basic support for debian packaging

To generate runtime and development packages one can use the following commands in the mlog's build directory:

```bash
cpack --config debian/Runtime.cpack
cpack --config debian/Development.cpack
```

On my debian installation the commands give the following:
```bash
dodzerik@b1:~/build/mlog$ cpack --config debian/Runtime.cpack                         
CPack: Create package using DEB                                                       
CPack: Install projects                                                               
CPack: - Run preinstall target for: mlog                                              
CPack: - Install project: mlog                                                        
CPack: -   Install component: runtime                                                 
CPack: Create package                                                                 
CPack: - package: /us/dodzerik/build/mlog/mlog-0.2.0-Linux-runtime.deb generated.     
dodzerik@b1:~/build/mlog$ cpack --config debian/Development.cpack                     
CPack: Create package using DEB                                                       
CPack: Install projects                                                               
CPack: - Run preinstall target for: mlog                                              
CPack: - Install project: mlog                                                        
CPack: -   Install component: development                                             
CPack: Create package                                                                 
CPack: - package: /us/dodzerik/build/mlog/mlog-0.2.0-Linux-development.deb generated. 
```

The development package depends only the runtime package. The runtime package depends on nothing. Probably a dependency on Boost should be added

The development package, among headers files, install MlogConfig.cmake file to ${CMAKE_INSTALL_PREFIX}/lib/cmake. The file can be used in external cake projects which use mlog. Such projects should be configured as follows (let's ${CMAKE_INSTALL_PREFIX} be /usr):

```bash
cmake -DMlog_DIR=/usr/lib/cmake
```

After this the project can use mlog as a normal cmake project, i.e 

```cmake
find_package(Mlog QUIET REQUIRED)
include_directories(
  ${Mlog_INCLUDE_DIRS}
)

link_directories(
  ${Mlog_LIBRARY_DIRS}
)

add_target(my target mytarget.cpp)
target_link_libraries(mytarget  ${Mlog_LIBRARIES})
```