General build cleanup

Consolidate buildupdate.sh, /build/buildupdate.mono.sh, and /build/buildupdate.win.sh => /build/buildupdate.sh
Combine Palaso.sln and Palaso VS2010.sln => Palaso.sln (VS2010 and VS2013 compatible)
Remove unused files: PalasoError, Palaso.sln, .hgignore
Since exiftool.exe is replaced with taglib-sharp, remove exiftool from build configuration
Fix SIL.ScriptureUtils.Tests reference to nunit.framework.dll
I had merged the existing scripts, and hand-edited to handle different dependencies. I'll take a look at BuildUpdate with the plan of either:
a) restoring the separate build scripts
b) getting BuildUpdate to create a combined file