FEAT: Configurable language codes

[carlwilson]

• added <languageCode> element to jhoveConfig.xsd and ConfigHandler;
• set the module.language property in JhoveBase;
• changed config schema location to OPF servers;
• tests for ConfigHandler language, including defaults for bad values; and
• tidied ConfigHandler formatting some.

This builds on the work done by @leefrank9527 in #693, thanks. Closes #643

[codecov]

Codecov Report

Merging #729 (f9580a3) into integration (1b9858b) will increase coverage by 0.04%.
The diff coverage is 55.29%.

@@                Coverage Diff                @@
##             integration     #729      +/-   ##
=================================================
+ Coverage          46.46%   46.51%   +0.04%     
- Complexity          1054     1057       +3     
=================================================
  Files                 57       57              
  Lines               9059     9073      +14     
  Branches            1606     1609       +3     
=================================================
+ Hits                4209     4220      +11     
- Misses              4308     4310       +2     
- Partials             542      543       +1     

Impacted Files	Coverage Δ
...main/java/edu/harvard/hul/ois/jhove/JhoveBase.java	42.13% <0.00%> (-0.18%)	⬇️
.../java/edu/harvard/hul/ois/jhove/ConfigHandler.java	61.41% <56.62%> (+3.15%)	⬆️

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