Fixes for postgresql integration tests.

Added concept of unmodfiable data types.
Type like int4 should not have a size specified.
E.g. int4(10) is invalid

Refactored the code for reading a default value.
Using a Scanner as it provides easy methods to check if a value is valid.
Added check for whether a BIT value is actually a string of value 'true' or 'false.
This is the case in postgresql.
Added fix for reading column size in H2.

On my Ubuntu box, H2 sets the column name for the size of a column to CHARACTER_MAXIMUM_LENGTH and the label to COLUMN_SIZE.
When  mapping columns I think in general we should use the column label and not the column name.
The column label will fall back to the name if no label is specified. If one is specified then typically it's specified for a reason (standards compatibility).

Removed old h2 jar from database test drivers.
renamed test so we can have a specific test for AbstractSQLChange
Fixes for Hsqldb Integration tests and CORE-1229

Added fix suggested for Holger Willebrandt for GetViewDefinitionGeneratorHsql.
Tested and it works fine now.

Revved hsqldb to version 2.2.9
This version adheres to the sql standards.
It contains a TABLE_CONSTRAINTS table in the information_schema.
Added checks for HsqlDatabase to Int, Double, BigInt and Boolean toDatabaseType methods.
Sizes were being incorrectly appended. E.g. boolean(0);

Fixed bug with setting defaultSchemaName.
The default schema name that is set should be corrected by the implementing database.
E.g. setting 'liquibaseb' as the default schema name for Hsqldb is actually setting 'LIQUBASEB' as the defualt schema name.
This difference means that snapshot checks fail to realize that the DatabaseChangeLogLock table already exists.

Modified the correctObjectName method in AbstractJdbcDatabase.
Based on a conditional property unquotedObjectsAreUppercased, unquoted objects are either uppercased or lowercased.
This reflects typical database handling. Quoted objects don't have their case changed in any database that I've worked with.
Fix for CORE-1251

Overide doGetDefaultSchmea instead of getDefaultSchema so an alternative default schema can actually be set.
Small performance enhancement for checksum generation.

When any is set as a valid checksum, skip generation of the checksum as it is not
needed.
Documented and tested AbstractSQLChange
Documented and tested ChangeFactory
Postgresql does not handle nvarchar type.

NVarchar should be converted to varchar for Postgresql as it does not recognise
nvarchar.
Documented and tested ChangeMetaData
Documented and tested ChangeMetaDataParameters
added appliesTo(DatabaseObject) convenience method
Merge pull request #92 from vorbis/postgresqlFixes

Fixes for postgresql integration tests.
Merge remote-tracking branch 'origin/master'
Added comment to re-evaluate code added in pull request 92
Merge pull request #94 from vorbis/h2ColumnFix

Added fix for reading column size in H2.
Merge branch 'hsqldbFix' of https://github.com/vorbis/liquibase into vorbis-hsqldbFix

Conflicts:
	liquibase-core/src/main/java/liquibase/snapshot/jvm/UniqueConstraintSnapshotGenerator.java
Merge remote-tracking branch 'origin/master'
Added integration test outputs to .gitignore
Merge pull request #96 from vorbis/h2DefaultSchemaFix

Fix for CORE-1251