progress with Samples Grid

Created by: mguijarr

Here are some commits, most of them bringing new features to Samples Grid:

• better layout
• new buttons and actions: Select All, Add Samples
• Add Samples really add samples to the queue
• filter feature is on its way

And 2 general enhancements:

• no default log file (if no log file is specified, log goes to stdout)
• new Main component, containing the global layout of the application (NavBar + Bootstrap grid)