TEIIDDES-2139 / 2237 - Adds a password token to connections and servers

* Since the url of the server is not unique, it is possible to overwrite
  passwords held in secure storage with values from other servers or
  jdbc connections.

* Adds a pass token to the servers and the connection properties which
  provides a unique reference to the password stored in secure storage

* Pass token generate with 1-way hash of the password and the url

* By carrying the pass token, each connection / server retain their unique
  password without actually holding it in the clear or revealing it until
  its actually used

* TeiidConnectionTest
 * Unit tests added for possible use cases involving password permutations
   hopefully ensuring that previous password methods of storage are taken
   into account and things stay backward compatible

* [*]SecureStorageProvider
 * Adds existence method to test a node keys existence since null is a
   valid password value

* TeiidConnectionInfo
 * Removes caching password entirely since it just confuses
 * Explicitly tests for storage password existence rather than just checking
   whether retrieved password is null
 * Only if there was a password when changing url fields is the password
   retrieved and updated with the new url
Miscellaneous Fixes

* TeiidServerEditor
 * Avoid executing runnable if form has already been disposed

* ExecutionAdmin
 * pingJDBC should not call admin.deploy but adminSpec.deploy since the
   deploy method changed names between Teiid 7.7 and 8.0
Merge pull request #382 from phantomjinx/master

TEIIDDES-2139 / 2237 - Adds a password token to connections and servers