Reset version to SNAPSHOT after creating a new milestone release.
Add support for "getFirst" as indicator to get the first observation.
Add support for procedure descriptions linked to externals (http://) sources, only for DescribeSensor.
Merge branch 'develop' of https://github.com/52North/SOS into develop

* 'develop' of https://github.com/52North/SOS:
  Add contributing section to README.md file
  Update RELEASE-NOTES for 4.1.2
  Update version to 4.1.2
  Update HiberanteFeatureQueryHandlerTest to extend from HibernateTestCase.
  Typo
  Fix issue when transactional is supported but a procedure has not validProcedureTime entry.
  Fix invalid time in JSON-InsertObservation example
  set version to 4.1.2-SNAPSHOT
  Correcting version numbers
  Trying to make the fix more general than present use case.
  fixes 52North/SOS#149
  Increase version number.
MySQL/MariaDB datasource for custom mappings

installer is usable if 'MySQL/MariaDB Custom Mapping' is chosen
Merge pull request #157 from autermann/feature/custom-mysql-datasource

MySQL/MariaDB data source for custom mappings
Update RELEASE-NOTES
Merge pull request #158 from CarstenHollmann/feature/sensordescription_from_url

Feature/sensordescription from url
Set OGC unknown URL instead of URN as xlink:href value of sampledFeature
Add published flag for series, default is true. If published flag is F = false, the GetObservation and GetDataAvailability responses does not contain any values of the series with published flag = false.
Add published flag to SQL scripts and add update scripts
Update version to 4.1.3
Merge pull request #159 from CarstenHollmann/feature/publish_flag_for_series

Add publish flag for series
Allowing for TextValue to be put into WaterML2.0 result and xml escaping it
Merge branch 'master' into develop
Add series published flag to SQL create scripts and add update statement to SQL update scripts
Fix missing import after merging master into develop
Fixing pom version to 4.2.0-SNAPSHOT
Merge pull request #160 from jiwalker-usgs/develop

Allowing for TextValue to be put into WaterML2.0 result
Fix problem with query for Spatial Filtering Profile envelope for database that do not support the spatial extent function.