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