Fix spelling for nagios check message.
Merge pull request #761 from dpiddy/fix-nagios-spelling

Fix spelling for nagios check message.
Fail the source installation if there is an error on the way

In response to #595
Revert "Fail the source installation if there is an error on the way"
as it's breaking report sending in case of failure
This reverts commit 2d5428b1358e742feb2641ec8655cbe4ede41f66.
Turn ssl validation of http_check into an option

Fixes #770.
Merge from master.
Revert source install `set -e`