Move some utility functions into SqlUtils.

* src/main/java/org/glom/web/server/libglom/Document.java:
  Move getSqlDialect()
* src/test/java/org/glom/web/server/SelfHosterPostgreSQL.java:
  and move quoteAndEscapeSqlId()
* src/main/java/org/glom/web/server/SqlUtils.java: into here.
* src/test/java/org/glom/web/server/SelfHostExampleTest.java:
  Adapt.
SqlUtils: Slight JdbcConnectionDetails cleanup.

* src/main/java/org/glom/web/server/SqlUtils.java:
  Make JdbcConnectionDetails static and do some checks before
  creating it in getJdbcConnectionDetails().
Initial implementation of a users database.

* src/main/java/org/glom/web/server/SqlUtils.java:
  Make createField() public so we can use it to create SQL queries
  for the users database.
* src/main/java/org/glom/web/server/users/UserDatabase.java:
  An overly-simplified API and implementation of a users database,
  based on the table structure in the Spring Security documentation.
* src/test/java/org/glom/web/server/users/UserDatabaseTest.java:
  Test the API.
* src/test/java/org/glom/web/server/SelfHoster.java
* src/test/java/org/glom/web/server/SelfHosterMySQL.java
* src/test/java/org/glom/web/server/SelfHosterPostgreSQL.java:
  Modify these so they can be used to self-host databases other than
  just databases for Glom documents, so we can use it to self-host
  a users database during testing.
Correct the OnlineGlomConstants.hu filename
Add GlomPlace.

* src/main/java/org/glom/web/client/place/HasDocumentPlace.java:
  Move most of the Tokenizer to a parent class, so we can have
  system-wide URLs that do not involve a particular document.
Add GlomActivity.

* src/main/java/org/glom/web/client/activity/HasDocumentActivity.java:
  Move some of the implementation to:
* src/main/java/org/glom/web/client/activity/GlomActivity.java:
  We do not need to use this for non-document-specific URLs,
  but it is nice to separate its generic utility methods out.
Added the start of a UserRegister place/activity/view.
pom.xml: Update versions of some gwt stuff.
pom.xml: Update more dependency version numbers.
pom.xml: Require a revent maven version.

This lets us use later plugin versions, as suggested by
mvn versions:display-plugin-updates
pom.xml: Update plugin versions.
pom.xml: Update spring-security-* versions.
pom.xml: Update the guava version.
Update from jooq 2.6 to 3.