remove Confluence and Atlassian references from allthethings

content/events/august_2014_uno_hcc_workshop.md

content/events/hcc_condor_workshop_2013.md

content/events/hcc_fall_kickstart_2015.md

content/events/hcc_fall_kickstart_2016.md

content/events/hcc_matlab_workshop_2013.md

content/events/hcc_mpi_workshop_2013.md

content/events/hcc_qiime_workshop_2016.md

content/events/hcc_spring_workshop_uno.md

content/events/hcc_users_group.md

content/events/hgrlab_anvil_presentation.md

content/events/instructions_for_52016_allinea_workshop.md

content/events/july_2014_bioinformatics_workshop.md

content/events/june_2013_osg_workshop.md

content/events/june_2014_bioinformatics_workshop.md

content/events/june_workshop_series_2017.md

content/events/june_workshop_series_2018.md

content/events/nebraska_supercomputing_symposium_12.md

...vents/october_2014_hcc_workshop_college_of_engineering.md

...ember_2014_hcc_workshop_earth_and_atmospheric_sciences.md

...pentry_open_science_grid_workshop_unl_january_6_8_2016.md