Better GIT lock management and error display

[cristianuibar]

This is how it looks like and maybe we can do something better? Even display an error message?

Click Here for Error Log

``` Warning: fopen(/tmp/.gitium-lock): failed to open stream: Permission denied in /sites/wp.site/files/wp-content/plugins/gitium/functions.php on line 219 Warning: flock() expects parameter 1 to be resource, bool given in /sites/wp.site/files/wp-content/plugins/gitium/functions.php on line 224 . --||-- . Warning: Timeout when gitium lock was acquired in /sites/wp.site/files/wp-content/plugins/gitium/functions.php on line 250 Warning: flock() expects parameter 1 to be resource, null given in /sites/wp.site/files/wp-content/plugins/gitium/functions.php on line 240 Warning: fclose() expects parameter 1 to be resource, null given in /sites/wp.site/files/wp-content/plugins/gitium/functions.php on line 241 ```

[DenisFlorin]

Fixed in #187 by dynamic tmp detection function.