Don't use postgres unless --with-postgresql.

This is in line with what the mysql m4 script does, and prevents the unit tests
from failing if the libs are present but pg is not running.

Also, in configure.ac, correct POSTGRESQL_LIBS -> POSTGRESQL_LDFLAGS.
Merge pull request #12 from mgatny/fixup_autotools_postgres

Don't use postgres unless --with-postgresql.
scripts for jenkins
Merge pull request #13 from mgatny/master

scripts for jenkins
Fix up compiler warnings.
Merge pull request #14 from mgatny/fixup_compiler_warnings

Fix up compiler warnings.
Bootstrap and configure before generating
Merge pull request #15 from mgatny/fixup_build_with_generate_jenkins_script

Bootstrap and configure before generating
Ubuntu jenkins script installs jruby.

Speeds up codegen.
Merge pull request #16 from mgatny/fixup_build_with_generate_jenkins_script

Ubuntu jenkins script installs jruby.
Update performance tests to reflect real-world message parsing scenarios
Optimize DataDictionary::getGroup() and DataDictionary::isGroup() methods. This change increases message parsing and validation performance in different scenarios by 12%-35%
Allow FieldBase class to construct m_string member in-place using message string offsets. Improves message parsing performance by up to 10%
Add method FieldMap::getFieldIfSet(). No need to use isSetField() + getField() methods to query fields with optional presence. Small refactoring
More accurate calculation of the size needed to hold message string representation. Yields up to 14% of speed increase during message encoding. Small tweak in MessageSorter class.
Improve error reporting for message length, data field length and checksum calculations
Improve integer-to-string serialization performance. Use 'int' data type instead of 'long' in the IntConvertor
Improve field tag parsing performance and error reporting when tag contains invalid format