Improving importbox.sh script

This is since I think (I hope) i have improved the initial importbox.sh. This one is more descriptive, and has few more options. Also, the attempt was made to create a more generic bash script which uses Vagrant.generic file (the actual name of known vagrant repositories names is changed to generic newBox).

Please, do note that the step [6]: "Executing the command: vagrant up --provider which provider?" could be improved, but still one can have argument that there are so far 4 providers, and more than 1 can be present at the time of testing. The improvements will be to scan through "vagrant box list command and find out if only one provider is present, or more?

Please, also note that the first line uses bash.