sosreport: fix name matching of the generated report file

In src/kimchi/model.py, function _sosreport_generate() collects the
generated debug report through pattern matching against the file name.
In the current implementation, it actually collects the last file in the
matching file set. This works most of the time but is not correct.

This patch fixes the problem, skips on *.md5 file, collects the correct
file, and raises exception when no file can be found.

This patch also renames "fi" to "reportFile" to improve readability and
ease of searching.

Signed-off-by: Zhou Zheng Sheng <zhshzhou@linux.vnet.ibm.com>
Tests: Generate UUID and use as temp report file name

test_debug_reports runs the debug report tool to generate report file.
It's possible that the tool runs too long and timeout expires. While the
test is over, the tool continues to run and generate report file. The
leftover report file causes conflict with report file name used in the
the next run of test_debug_reports.

This patch generates UUID for each run and use it as the part of file
name. It also deletes all leftover files generated from previous runs.

Signed-off-by: Zhou Zheng Sheng <zhshzhou@linux.vnet.ibm.com>