Set a default data directory

[ar13pit]

Directory to save models for image and speech recognition

Before merging correct the paths in targets (tue-robotics/tue-env-targets#29)

[MatthijsBurgh]

Check https://github.com/tue-robotics/tue-env/blob/master/setup/tue-data.bash. Data has always been stored in ~/ros/data(/private), so keep it there.
I don't know if this was designed for rosbags, logged data or also models.
Steps to take:

• First analyse tue-data, maybe ask @Timple or @svddries
• Design new system/ design updated system
• Implement it

[ar13pit]

I did see that but the keras models are being downloaded to a different location
https://github.com/tue-robotics/tue-env-targets/blob/master/ros-image_recognition_keras/install.bash#L3

So thought of generalizing the location. But the question then is why is the keras model not being placed there?

[MatthijsBurgh]

See updated comment, now I will be offline again.

[ar13pit]

Closing this PR as this issue needs more discussion and maybe a new design for data management of an env workspace.