Upgrade comms/gammu from v1.39 to 1.40

Full list of changes:

• Added SMSD configuration option RetryTimeout.
• Removed non configurable sleep after failed message send.
• SMSD now tries to store whole decoded text for concatenated messages in the first entry in database.
• Improved compatibility with Sierra SL8084TR.
• Added support for delivery reports stored in SR memory.
• Configure CNMI parameters for AT driver.