update spi to reflect the most recent changes to the lld
Added ADC, PWM, I2C, to documentation
Merge branch 'master' of github.com:PSAScapstone2014/Documentation
Changes to Section 2. Added a short description about the Variables table.
Changes to the second section. Modified description of the Test Cases table.
Added section headings.
Changes to the method description section. Updated method descriptions.
Added section on Valgrind.
Added links to the table of contents.
Changed the echo_test method description.
Merge branch 'master' of github.com:PSAScapstone2014/Documentation
Updated GPT Documentation