Merge pull request #373 from eric-wu/develop

Merge down from release-1.23: Change DOI target URL to synapse.org
Merge pull request #375 from eric-wu/develop

Merge release-1.23 patch to develop -- 	 Remove the redundant URL encoding
PLFM-1648: persist FileHandle IDs with Submission objects
Merge pull request #376 from bkng/develop

PLFM-1648: persist FileHandle IDs with Submission objects
Temp fix for PLFM-1835. Do not merge back into develop branch.
Merge pull request #377 from xschildw/release-1.23

Temp fix for PLFM-1835. Do not merge back into develop branch.
PLFM-1648: Code review changes
fix
Merge pull request #381 from john-hill/PLFM-1840

fix
Merge pull request #380 from john-hill/PLFM-1840

fix
Merge pull request #378 from bkng/develop

PLFM-1648: Code review changes
allow files in studies
Merge pull request #382 from john-hill/PLFM-1841

allow files in studies
Merge branch 'release-1.23' into develop
Merge pull request #383 from john-hill/develop

Develop