Fixes an issue with stylesheets associated via handle.

Cf. #24099

HttpUrlConnection by default sets an Accept header that includes HTML
which causes the TextGridRep frontend to display a landing page instead
of delivering the data. We now explicitely request XSLT there.

Fixes #24099

Refs #24099

Deleted Jenkinsfile due to not working pipeline :-( We have to investigate, how we can setup a working build process for more than one branch. should work, but not today...

jenkinsfile added, builds (or will build) develop and master branch, all versions including "SNAPSHOT" will be deployed to snapshot aptly and nexus repositories, all versions without "SNAPSHOT" will be deployed to release aptly and nexus repositories (as soon I have created the appropriate jenkins pipeline. testing now...

TextGrid Aggregator Release 1.4.9

* switched preview mode to the new site
* support the sandbox in zip export
* fixed zipping search results that contain only filters, no query
* zip: streaming mode is true by default

Cf. #22310

Refs #22310

Refs #22310

Refs #22310

Aggregator 1.4.8 adds support for delivering a table of contents, adds a debian
package to support deployment via our puppet architecture, and supports nested
HTML in the embedded view. It also works around a bug in Java 1.8 that created
TEI headers which were invalid XML.