Fix small typo
[SSHD-247] Enable SCP and SFTP in the default distribution
Also add an option to select the IO provider
Fix distribution readme
Remove quotes in SCP transfers
Make sure the NIO2 IoService can't be loaded if not on JDK 7 so that SSHD falls back on Mina correctly
[SSHD-248] Upgrade to mina 2.0.7