DS-1823 move dspace.url to build.properties

dspace.url is now independent from baseUrl
add context to  two methods parameters  to have monthly statistics localised
First pass at a third-party plugins directory
Factor the loader out of PluginManager, and provide a minimal unit test.
Add test of loading from a JAR.
Correct loading from JAR.
Fixes DS-2113: JSPUI HTML5 upload should store Bitstreams...
XOAI add bitstream description to xoai metadata format
Add sample configuration and document it
Fix to avoid connection pool exhaustion for slow downloads and big files
Put the Item's persistent identifiers into the DRI document.
Add Altmetric.com badging
fix display: declare the confman namespace used here
Rename module configuration to be a little less generic
Switch to direct use of dc.identifier.uri metadata
Make identifier metadata field name configurable
Add PlumX
Move XMLElement of community.subcommunities to getter to prevent errors
REST writeStats to reuse existing context
Merge pull request #685 from mwoodiupui/DS-1222

[DS-1222] Alternative Metrics - Framework, Integration of AltMetric and PlumX