Update 51-DeviceConnection.md
Fix the GSM off issue and implement a simple workaround for the simcard logic issue.
Switch the SIM status and power pins, they were reversed.
Merge pull request #143 from amcgee/fix-gsm-issues

Score.  Merging this then.
add export in front of four PATHs
Fix gsmtool example command syntax

The MIB address argument goes after the command designation, not before.
Merge pull request #144 from kgcooke/dev

add export in front of four PATHs
Remove old cruft from README

The link to the documentation page should be enough
Move modtool documentation to the doc folder so it's accessible.
Merge remote-tracking branch 'upstream/dev' into dev
Remove extraneous backtick.
Merge branch 'dev' into feature-sim-8bit