Implement -Z (--retrievable_by_cert) option.

Allow specified entity to retrieve credential w/o passphrase (trusted
retrivers)
Conflicts:

	myproxy/src/main/java/org/globus/myproxy/MyProxyCLI.java
Increase Myproxy default proxy key bits to 2048 (as in C version)
Fix myproxy -Z option Conflicts:

	myproxy/src/main/java/org/globus/myproxy/MyProxyCLI.java
fix log message in SigningPolicyParser
Missing dependency
Manual backport of pull request 59 due to git am issues