First Unit C++ tests

[miquelflorensa]

Unit tests for architectures:

• FNN
• FNN Heteroscedastic
• FNN Full Covariance
• FNN Derivatives

Usage: After compiling the project use:

• build/main test all (to generate all data comparing files)
• build/main [architecture] (to generate the architecture data files)
• build/main test (to execute all the tests)

A lot of changes have to be made, but it is a first approach.