Integration with postgresql

[woodbri]

This is a TODO list to get this code ready for integration with postgresql.

1. we need to create C code to read the user data from the database
2. we need a C++ wrapper function that will take the C structs of input data and create our vrp object and initialize it with the C data structs. This implies writing xome new problem loading methods
3. the C++ wrapper will solve the problem and return a C struct with the results data and catch any throws and return an error if needed
4. CONFIG singleton probably needs to be rethought as I'm not sure this will work in postgresql
5. STATS singleton probably needs to be rethought as I'm not sure this will work in postgresql
6. all std::cout needs to be change to a file logger class
7. all plotting need to be removed or disabled
8. all asserts need to be off and/or converted to throw errors that can be caught in the wrapper to report back to the postgres user.
9. we need to integrate the build of the vrp stuff with the build of the postgresql stuff

[woodbri]

Starting a branch "postgresql" to start this work in. https://github.com/woodbri/vehicle-routing-problems/tree/postgresql/postgresql