Format testcase.xsl and testresult.xsl by `xmllint --format`

Reference: http://xmlsoft.org/xmllint.html
This just formats the .xsl files' indent with 2 spaces, empty line.
`tests.xml` looks the same as before.
Replace tab with 2 spaces for .xsl file indent
Merge pull request #47 from zqzhang/zqzhang/xsl-format

Format testcase.xsl and testresult.xsl by `xmllint --format`