[Halld-offline] hdpm 0.7.3

[Alexander Austregesilo]

Dear Colleagues,

hdpm 0.7.3 has been released.

https://github.com/JeffersonLab/hdpm/releases

For help with updating, see 
https://github.com/JeffersonLab/hdpm/wiki/Usage or try "hdpm selfupdate".

This release:
1. matches https://halldweb.jlab.org/dist/version_2.27.xml and therefore 
includes the following updated packages:
- RCDB 0.03
- CCDB 1.06.06
- AmpTools 0.9.3
- SQliteCPP 2.2.0

2. adds GNU scientific library (gsl) to the prerequisites

3. was tested on CentOS7/RHEL7 and Ubuntu16, but not on CentOS6/RHEL6 or 
macOS

Please let me know if you experience any problems or in case you want to 
volunteer to test it on macOS.

- Alex