Don't crash if the connection has an error
set encrypted flag to None for root device

"AWS API doesn't support any value for this flag for the root device of
a new instance"

see: boto#2587

closes gh-455
move try/except from is_up to is_ssh_up
Merge branch 'fix-conn-reset-by-peer' into develop

closes #465
remove t2 types from placement group types list
bump version to 0.95.6
Changelog: update for 0.95.6 release
Merge branch 'hotfix-0.95.6' into develop
Allow specifiying bid for master
run user script on node add
Work on options for number of workers per machine
Save the userdata_scripts used in tag
Wait on completion of user script
Revert changes to sentinel
Fix to user data scripts loading
Update services
Initial commit of SGEInstaller
on_add_node and on_remove_node for sgeinstaller
HACK fix for date parsing
added slots_per_host option to load_balance