Huge update to the TDG branch, bringing it all the way up-to-date with the main GSMSHIELD branch

[madmaze]

This pull request includes:

• reformatting of everything, spacing/line-endings
• includes changes from @MarchMartines to move strings to flash memory, save RAM
• fixes to httpGet() and httpPost()
• fix to setting GSM_ON and GSM_RESET to output before writing to them