enh: new entities

* new entities: standard error, resMS, stat_image_properties
* couple of fixes for excursion_set_it.
* update of provn, json and ttl serializations and pdf and svg exports.
Applying changes agreed on 25/11/13 meeting

* modified entity names: contrast_standard_error_map_id and
residual_mean_sum_of_squares_map_id
* design matrix stored as csv instead of png
* contrast name also stored in contrast_id entity
Fix: png -> csv

Also renamed residual_mean_sum_of_squares_map_id entity to
niiri:residual_mean_squares_map_id
add: https://central.xnat.org/data/projects/PALS/subjects?format=json
Remove optional placeholders

Delete optional placeholders in relations 'used', 'wasGeneratedBy' and
'wasAssociatedWith'.
New "data scaling" entity

In agreement with NIDASH-DDWG call on December 2nd.
Create activities and entities to get closer to Nipype
fix: still working on json-ld formatting
Merge branch 'fslUpdate' of https://github.com/cmaumet/ni-dm
Merge pull request #13 from cmaumet/newActivity_dataScaling

New entity for data scaling
Merge branch 'master' of github.com:jbpoline/ni-dm

Conflicts:
	examples/spm/spm_results.provn
	examples/spm/spm_results.svg
update svg and pdf
fix: placeholder outside parenthesis
rebasing gllmflndn code and adding estoimation activity
Merge pull request #3 from cmaumet/gllcoderebasedwithactivity

Rebasing according to ni-/ni-dm and keep statistical_estimation activity
Merge pull request #11 from gllmflndn/master

enh: new entities
update of all serializations.
Merge pull request #15 from gllmflndn/master

update of all serializations.
New SPM examples: 2 contrasts
Merge pull request #16 from cmaumet/newspmex

New SPM examples: 2 contrasts