Right now, BlenderVR does not properly handle paths containing ~ or ~user in the configuration xml. As a low-priority convenience, it would be useful to allow users to specify such paths.

Steps to reproduce:

1. Create a configuration xml with either <starter blender='~/my/path/to/blender'> or <blenderplayer executable='~/my/path/to/blenderplayer'/>
2. Attempt to run any sample using this configuration.

Expected behavior:
The sample should run without errors if the given path points to a valid blender executable.

Observed behavior:
Error message "Error : invalid blender path" or "Cannot start blenderplayer"

I have implemented a (trivial) fix for the specific issue of the blender and blenderplayer executables at wphicks/BlenderVR-source@6bbccfa, but it would be better to make sure that this issue does not exist for any other configuration option. Best of all would be to handle all configuration paths via some consistent path normalization function.