mmirs_pipeline_taskfile: Implement imaging data processing workflows

[astrochun]

SAO TDC has now developed an IDL pipeline to reduce imaging data. This is the code:
https://bitbucket.org/chil_sai/mmirs-pipeline/src/master/pipeline/mmirs_reduce_imaging.pro

At the moment, mmirs_pipeline_taskfile does not include the imaging datasets (only does longslit and MOS). This will need to be changed to include and a separate function is needed to process each imaging datasets. This is occurring within the organize_targets() function.