gitlint: Add options to enforce the Open IoT SDK commit guidelines

This is the list of commit guidelines that are enforced by this change:

Separate subject from body with a blank line
    - body-first-line-empty
Commit message subject is allowed to be 72 characters wide
    - title-max-length
Capitalize the subject line
    - title-match-regex
Do not end the subject line with a period
    - title-trailing-punctuation
Subject line must include a prefix that identifies the subsystem being
changed
    - title-match-regex
Wrap the body at 72 characters
    - body-max-line-length

Signed-off-by: Anna Bridge <anna.bridge@arm.com>