Reorganize data directory

 - Split out autopkgtest output into ${debci_data_dir}/autopkgtest/:
   This now contains a full directory for each test run with all of
   adt-run's --output-dir files. This provides access to individual test
   stdout/err logs, the package version lists, and additional artifacts
   that tests produce. With this, autopkgtest/ becomes eligible for being
   on a remote file system and can be synced/rebuilt independently of the
   metadata.
 - Use run IDs with format YYYYMMDD_HHMMSS[machine or tags] instead of the
   old YYYYMMDD-n as the former works for a distributed file system and
   remote workers.
 - base.txt is now replaced with adt-run's testbed-packages output file.
 - test-packages.txt gets dropped as there is no need to keep it around
   permanently. Build it from the per-test -packages logs from adt-run.
 - Move status.json into status/ directory and remove the redundant
   latest.json.
 - Move packages.json into status/ directory.
Add tools/convert-data: Convert data/ directory to changed format

This can be dropped again after running it on the production debci instance.
app.js: Filter out query strings from URL for constructing the .json URLs

This fixes wrong URLs after using the package search field.
backends/schroot/test-package: Drop unused temporary dir
backends/*/test-package: Write exit code into "exitcode" file in output dir

With that we retain it even when we switch to asynchronous/remote processing.
backends/fake/test-package: Write log file into output dir, like adt-run
Prepare for async/remote adt-run

Move test result evaluation, log and meta data creation from debci-test to
debci-generate-indexes. This prepares the way for running adt-run
asynchronously or remotely, and picking up the results from the autopkgtest/
data directory.
app.js: In the per-package test list, add link to autopkgtest files (artifacts)
debci-status --all: Output a list also if there is only one package

Otherwise the web interface is broken, as the data structure is unexpectedly
different.
convert-data: Ignore missing json files

Some .log files in our existing data are missing an accompanying .json file.
Ignore those instead of crashing.
debci-status --all: Sort package names so that they appear sorted in the web UI
Merge remote-tracking branch 'mpitt/master'
debci-blame: replace usage of deprecated IO#lines method with IO#each_line