Normalize paths in JvmUtils

Fixes problem in Windoze where file paths cannot be so easily
converted to URLs.

Fixes gh-767
Monkey with process forking for Windoze

There were several problems to fix. 1) a bug in the
JDK (1.7 up to 7_60):

https://bugs.openjdk.java.net/browse/JDK-8023130

which we can work around by detecting buggy VMs and not trying
to use inheritIO. 2) File<->URL conversion is platform dependent
and we shouldn't make any assumptions. The problem in this case
was that file URLs contain a ":" so they can 't be added to a
path in UNIX, but on Windows you need the absolute path with the
colon. Solution: use Files on the classpath for spring-boot:run.

Hopefully also fixes gh-767