Nikon P7100 doesn't connect as a mass storage device

Using Usb_modeswitch as discussed above won't work, but there are some alternative ways of accessing your photos , at least one of which should work for you:

On some cameras (like my friend's Nikon D70) there is an option on the camera that allows you to connect it to the computer as a mass storage device. However, on your P7100 I don't think there is that option after looking through the specs listed at the official site and studying the manual.

However, there is one option that might work for you; as you know your camera is a MTP device you could try mounting it manually with gvfs-mount and the gphoto2 protocol which has support for MTP devices. All you need to do is find (as you have done already) the usb bus location of your camera (i.e. the two numbers: Bus 002, Device 007), although that will probably change every time you connect your camera, so remember to check with lsusb. Enter, for example:

gvfs-mount gphoto2://[usb:002,007]

Then the camera should be available for you to import pictures via applications like gthumb, or at the very least you will be able to browse the .gvfs folder where it is mounted (enable hidden files in your file browser to see the .gvfs folder).

For Ubuntu 12.10 and later: the ~/.gvfs folder is now at /run/user/username/gvfs.

If the mount does not succeed, you could obviously take the memory card out and place it in a card-reader, but perhaps that is not what you want to do.