piuparts.py: set scriptsdir to /etc/piuparts/scripts and run this scripts by default.

Update piuparts.1.txt and README.txt accordingly.
dependencyparser.py: loosen the multiarch spec

Per the Multi Arch spec, a package dependency may have an ":any" appended to
the package name in a Depends-type spec. The dependencyparser module detects
and strips any occurance of ":any".

https://wiki.ubuntu.com/MultiarchSpec#Extended_semantics_of_per-architecture_package_relationships

Per #748426, lsb-core has an ":i386" multiarch modifier on a package name,
causing the dependencyparser to crash in piuparts-report, disabling all p.d.o
reporting.

http://lists.alioth.debian.org/pipermail/piuparts-devel/2014-June/005468.html

Leaving the proper lsb-core behavior to another venue, this change modifies
dependencyparser to be lenient about the ":" modifiers it accepts and strips.
changelog: fix whitespace
piuparts-report.py: De-indent global summary func

Remove four spaces of indent from the body of
generate_global_summary().
piuparts-report.py: Refactor global summary

Factor out the section sorting logic to from generate_global_summary()
to another function, sections_by_precedence().
Remove oldstable and older from p.d.o summary

There is a desire in the DDPO integration to add value to the Piuparts
column by showing more detail in the failures, and to winnow out chaff
in the reporting.

The details on how to do this are not fully developed. In the
meantime, as a first, interim, step, configure p.d.o to remove summary
reporting for section tests involving oldstable and older.
Remove stable dist results from p.d.o summary

Select this commit for further de-chaffing of the JSON summary.

Remaining sections are currently:

experimental
jessie
sid
sid2experimental
sid-nodoc
testing2sid
piuparts-report.py: Restore counts.txt to web

Commit 70fe80693 moved the counts.txt file, which drives the section test
result chart, from the web section directory to the master section directory,
making it no longer visible from a web view. This change restores a copy of
the counts.txt file to its original location, in the web section directory.
piuparts-report.py: Link to counts.txt

Below the chart on each section page.