ssl-proxies: Improve RFC 3820 compliance of key usage check

Each certificate in a certificate chain can have a key usage field.
The existing JGlobus code checks that each proxy certificate does not
have more key usages than the issuing certificate. This seems like
a sensible check, however it conflicts with the algorithm described
in RFC 3820.

The RFC states that all key usage (and extended key usage) extensions
of all proxy certificates and the EEC must be collected in a list and
the effective key usage computed by the intersection of all extensions:

   *  If a certificate is a proxy certificate with a policy other than
      id-ppl-independent, the effective key usage and extended key usage
      functionality of the proxy certificate is the intersection of the
      functionality of those extensions in the proxy certificate and the
      effective key usage functionality of the proxy issuer.

We have observed real-world proxy certificates that failed with the
existing check in JGlobus 2, even though they are valid proxies
according to the RFC. These proxies also work with JGlobus 1.
ssl-proxies: Introduce Enum for key usage fields

An Enum allows us to use an EnumSet which internally is
implemented as a bitvector. That is more efficient and
more convenient than using a boolean array.
Merge pull request #89 from gbehrmann/fix/keyusage

Improve RFC 3820 compliance of key usage check
Fix GlobusGSSContextTest

The GlobusGSSContextTest relies on having a credential, which then relies
on X509Credential class not having a cached copy of such a credential.
However, it does not ensure there is no such cached credential.

Since multiple tests (and test-suites) are run within the same JVM
instance, the effect is that, if another test-suite caches a
(deliberately) invalid, self-signed certificate then this cached
copy is returned instead of the expected certificate.

This patch fixes this problem by ensuring the cache is cleared.  It
introduces a (negliable) overhead as the cache is flushed between
tests; however, the additional robustness justifies this cost.

Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Make trustmanager reload CRLs by default.  Fixes #80.

Conflicts:

	ssl-proxies/src/main/java/org/globus/gsi/CertificateRevocationLists.java
	ssl-proxies/src/main/java/org/globus/gsi/trustmanager/X509ProxyCertPathValidator.java
Fix error message and list implementation, as suggested by code review.
ssl-proxies: Fix path validator when cert is lacking key usage extensions

270e41c6b59f5f113edd18cbad71956444f2090c introduced an enum to represent
key usage bits. The patch broke the key usage change for non-proxy certs
in that it did not deal correctly with the absence of the extension.
Merge pull request #92 from gbehrmann/fix/missing_key_usage_extension

ssl-proxies: Fix path validator when cert is lacking key usage extensions
ssl-proxies: Fix several race conditions

In particular the race in CertificateIOUtil has caused signing policies
be registered with the wrong hash. This in turn causes certificates
from the corresponding CA to be rejected.
Merge pull request #93 from gbehrmann/fix/races-signing-policy

ssl-proxies: Fix several race conditions
Fix tests
Merge remote-tracking branch 'upstream/master' into develop

Conflicts:
	gss/src/test/java/org/globus/gsi/gssapi/test/GlobusGSSContextTest.java
	ssl-proxies/src/main/java/org/globus/gsi/trustmanager/X509ProxyCertPathValidator.java
	ssl-proxies/src/main/java/org/globus/gsi/util/CertificateUtil.java
Cleanup imports