CMake build system

CMake build system for Caffe as suggest in #215 

Changes:
1. Tests are managed by CTest, but can be run as individual gtests or a batch gtest (test.test)
2. Building shared libs is controlled by BUILD_SHARED_LIBS flag set at configuration time (default is off)
3. Have yet to add Matlab wrapper
4. ~~Changed source tree in order to facilitate out-of-source build~~
5. Compiler must be specified before the first invokation of cmake (if default is other then gcc-4.6).
6. Test data location is dependent on the CMAKE_SOURCE_DIR variable; It is automatically set at make time.

Building tips:
```
mkdir build
cd build
CC=gcc-4.6 cmake ..
make -j8
ctest -v
```
(Not sure if `CC=gcc-4.6` is neccesary, but no other version works for me)

Options are specified at cmake invokation with -D flag. Example: -DPYTHON=ON
- ~~PYTHON~~ BUILD_PYTHON [default OFF]
- ~~MATLAB~~ BUILD_MATLAB [default OFF]
- ~~EXAMPLES~~ BUILD_EXAMPLES [default ON]
- ~~TOOLS [ON]~~ Not anymore, tools are built by defualt
- BLAS [atlas, open, mkl; default atlas]
- BUILD_SHARED_LIBS [default OFF]
- CUDA_TEST_DEVICE [default 0]

Remarks:
- Tested only under Linux Mint 16
- ~~Have yet to figure out why tools require recompilation of Blob.cpp~~