Merge pull request #18 from zthorson/master

GPIO.gpio_function() Fix
add simple uart test
better error handling of load_device_tree through adc, pwm, and uart
Give extra buffer space in export, and unexport functions for gpio that are more than 2 digits
Add new test case for 3 digit gpio
Increase buffer size of filenames for value, direction, and edge files
Merge pull request #21 from amscins/master

Some gpios are more than 2 digits long, and they do not export/unexport properly the string buffer is only big enough for 2 digits and 1 null char
The test_direction_readback fails, because gpio_get_direction wasn't properly null terminating the direction string
Adding common.h to event_gpio.c
Fix compiler error in gpio_set_value
Merge branch 'master' of https://github.com/adafruit/adafruit-beaglebone-io-python
Merge pull request #24 from amscins/master

The test_direction_readback fails, because gpio_get_direction wasn't properly null terminating the direction string
Fix PWM duty cycle so 0 is off and 100 is on.  Set polarity to 0 by default.
bump version to 0.0.14 and update changelog
bump version to 0.0.15
remove unused variables
Update README.rst
Update CHANGELOG.rst
fix for polarity not getting set properly, add polarity as optional parameter in start
Update CHANGELOG.rst