Payswarm Wordpress Plugin

Just trying to install

https://github.com/digitalbazaar/payswarm-wordpress

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Minor

Strangely I could not git clone from my amazon ec2 instance

fatal: https://github.com/digitalbazaar/payswarm-wordpress.git/info/refsdownload
error - The requested URL returned error: 403

Locally worked fine

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Minor

Trying wget

wget https://github.com/digitalbazaar/payswarm-wordpress/zipball/master

worked

make gave

ERROR: No git repository found, package building will fail.

Fixed with 'git init'

tho got a warning:

rm: cannot remove `payswarm-0.9.1/Makefile': No such file or directory
make: *** [package] Error 1

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So in the dashboard the plugin shows up, but when I clicked on activate I
got

Parse error: syntax error, unexpected ':' in /ebs2/
webappmarket.org/wp-content/plugins/payswarm/jsonld.php on line 746

    $rval = $subject->{$property} ?: array();

Is line 746 of my file

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