libtracker-control: Fix remnants of libtracker-miner in sources

Noticed by Michael Biebl. Thanks! :)
libtracker-control: Don't error with g_file_enumerator_next_file()

This has been happening lately for some people and it seems to be when
$prefix/share/tracker/miners/ doesn't exist. This is a broken install to be
fair, but Tracker should handle it more gracefully.

Added a NULL check on enumerator returned from g_file_enumerate_children().

https://bugzilla.gnome.org/show_bug.cgi?id=729968
libtracker-common: memory limits on systems with large amounts of RAM

On systems with large amounts of RAM get_memory_total() could overflow
and return a negative value, as a result memory would be limited to
MEM_LIMIT_MIN (which is 256 MB atm).
tracker-extract: Fix build with libav when libmediaaart is disabled

https://bugzilla.gnome.org/show_bug.cgi?id=728370
build: use pkg-config to look for which gdbus-codegen to use
tracker-search: Don't show "(null)" for nie:InformationElements with no nie:url
libtracker-control: _CFLAGS and _LIBS were not defined properly

This was causing the docs to fail to build in sandbox conditions
tracker-extract-oasis: Continue extracting if we find embedded tabs + line breaks

The following patch improves the oasis extractor on odt documents so
that it keeps extracting plain text content even when there are embedded
tab and line-break xml tags. Without this patch the extractor stops when
such a tag is encountered, and resumes typically at the next paragraph
or style/format change. This means extractable text is missed.
libtracker-data: Limit error message length

When a very long error message is eventually sent over D-Bus and the
original method call involves file descriptor passing, it hits Gnome bug
732615 and the sending process gets aborted.

https://bugzilla.gnome.org/show_bug.cgi?id=732839
all: Switch out GSettings "schema" property for "schema-id"

Was causing unit tests to fail and made distcheck impossible
docs/reference: Use FULL paths for DOC_SOURCE_DIR to avoid undefined warnings

This only occurs during distcheck because the path is not relative any more,
but it should be referenced from $(top_srcdir) anyway to avoid these warnings.
Release 1.0.2