Split and updated the Ubuntu and Debian instructions.

In particular, modifying the `fuse` group is no longer necessary on modern
versions of Debian.

Fixes #105.

docs/installing.md

@@ -14,7 +14,8 @@ pre-built binaries (i.e. you don't want to build from source), you need only
 ensure fuse is installed, then download and extract the latest release. The
 instructions slightly vary by distribution.
 
-## Debian and Ubuntu
+
+## Ubuntu
 
     sudo apt-get install wget fuse
     sudo adduser $USER fuse
@@ -24,10 +25,24 @@ instructions slightly vary by distribution.
 You may need to log out and then log back in to make sure that the change to
 the `fuse` group takes effect.
 
-On old versions of Debian, including the one in the Google Compute Engine image
-`debian-7` as of 20.6.07-20, `/dev/fuse` has incorrect permissions (cf.
-[this][stackexchange] StackExchange answer). Fix this with the following
-commands:
+
+## Debian
+
+    sudo apt-get install wget fuse
+    wget https://github.com/GoogleCloudPlatform/gcsfuse/releases/download/v0.6.0/gcsfuse_v0.6.0_linux_amd64.tar.gz
+    sudo tar -C /usr/local/bin -zxf gcsfuse_v0.6.0_linux_amd64.tar.gz
+
+### Old versions of Debian
+
+On versions older than Debian 8, it is additionally necessary to add yourself
+to the [`fuse` group][fuse-group]:
+
+    sudo adduser $USER fuse
+
+You may need to log out and then log back in to make sure that the change to
+the group takes effect. Finally, on these old versions of Debian, there is a
+bug causing `/dev/fuse` to have incorrect permissions (cf. [this][debian-bug]
+StackExchange answer). Fix this with the following commands:
 
 ```
 sudo chmod g+rw /dev/fuse
@@ -37,21 +52,25 @@ sudo chgrp fuse /dev/fuse
 Note that the operating system appears to periodically lose these changes, so
 you may need to run the workaround above repeatedly.
 
-[stackexchange]: http://superuser.com/a/800016/429161
+[fuse-group]: https://wiki.debian.org/SystemGroups
+[debian-bug]: http://superuser.com/a/800016/429161
+
 
 ## CentOS and Red Hat
 
     sudo yum install wget fuse
     wget https://github.com/GoogleCloudPlatform/gcsfuse/releases/download/v0.6.0/gcsfuse_v0.6.0_linux_amd64.tar.gz
     sudo tar -C /usr/local/bin -zxf gcsfuse_v0.6.0_linux_amd64.tar.gz
 
+
 ## SUSE
 
     sudo zypper install wget fuse
     wget https://github.com/GoogleCloudPlatform/gcsfuse/releases/download/v0.6.0/gcsfuse_v0.6.0_linux_amd64.tar.gz
     sudo tar -C /usr/local/bin -zxf gcsfuse_v0.6.0_linux_amd64.tar.gz
 
 
+
 # OS X
 
 If you already have the [Homebrew package manager][homebrew] installed, you can