Version 0.4.1

This release includes various fixes, enhancements, and additions.

Additions

• vnc command-line option. This installs a VNC server in the container, and optionally starts it at container runtime.
• mrtrix3 source installation

Fixes

• $PATH variable is set properly in neurodocker generate singularity.
• apt_opts="" and yum_opts="" now remove all options in apt-get install and yum install except for -y.
• allow conda environments built from yaml file to be activated at container runtime.

Enhancements

• Improvements in error-handling in neurodocker reprozip trace.
• mrtrix3 binaries are pre-built on centos 6.
• update nipype tutorial example