pom test: Correct spelling of Bundle-Developers header

Use constants.

Signed-off-by: BJ Hargrave <bj@bjhargrave.com>
pom test: Add asserts for Bundle-Developers and Bundle-SCM headers

Signed-off-by: BJ Hargrave <bj@bjhargrave.com>
pom test: Remove trim() calls

pom xml no longer corrupts the value with leading or trailing whitespace.

Signed-off-by: BJ Hargrave <bj@bjhargrave.com>