Harmonizing FSL example with SPM example

Few changes for consistency in spm_results.provn
 * Replace `nidm:coordinateSpace = "MNI"` by `nidm:coordinateSystem = 'nidm:mniCoordinateSystem'`
 * Add `nidm:fileName ` and `nidm:voxelToWorldMapping` in entities `niiri:search_space_id` and `niiri:excursion_set_id`
 * Add a `prov:label` to the `niiri:peak_XXXX` and `niiri:coordinate_XXXX` entities

Harmonizing FSL example with SPM example
  * Change namespace from `fsl` to `nidm` for the following terms: `fsl:statisticType`, `fsl:coordinateSpace` (changed to `nidm:coordinateSystem`), `fsl:dimensionsUnits` (changed to `nidm:voxelUnits`), `fsl:contrastMap`, `fsl:mask`, `fsl:dimensions`, `fsl:voxelSize`, `fsl:numberOfDimensions`, `fsl:heightThreshold`, `fsl:p` (changed to `nidm:pValueUncorrected`), `fsl:version` (changed to `nidm:softwareVersion`), `fsl:clusterSizeInVoxels`, `fsl:equiv_Z-statistic` (changed to `nidm:equivalentZStatistic`)
  * Change `fsl:label` into `prov:label` and add a `prov:label` attribute in each entity.
  * Add `nidm:contrastName` in entity `niiri:statistical_map_id` and `niiri:contrast_map_id`
   * Create two attributes `nidm:errorDegreesOfFreedom` and `nidm:effectDegreesOfFreedom` instead of a single attribute `fsl:degreesOfFreedom`
  * Remove `fsl:contrastVector = "1.000000 0.000000"` and `fsl:designMatrix = "designMatrix.png"` from entity `niiri:contrast_map_id`
  * Add `prov:location`, `nidm:filename` and `nidm:voxelToWorldMapping` to store full path, file name and voxel-to-world matrix respectively and remove `prov:value` in `niiri:statistical_map_id`, `niiri:contrast_map_id`, `niiri:search_space_id`, `niiri:excursion_set_id`
  * Removed `fsl:featVersion` in entity `niiri:software_id`
  * Removed `niiri:cluster_level_id` and `niiri:peak_level_id` and connected directly clusters `niiri:cluster_XXXX` to excursion set `niiri:excursion_set_id`.
  * Removed `niiri:stat_image_properties_id` entity.
  * Moved `fsl:reselSizeInVoxels` from `niiri:stat_image_properties_id` to `niiri:search_space_id`
  * Changed `hadMember` relationship by `wasDerivedFrom` when connecting two entities.
  * Coordinate defined by `prov:atLocation` in peaks.