Visualization only working once per session

[benmaier]

Whenever a second visualization is started, temporary files are not created correctly and thus won't be found

changing directory to /Users/bfmaier/.tacoma/web
starting server here ... /Users/bfmaier/.tacoma/web
preparing network
127.0.0.1 - - [16/Oct/2018 10:25:13] "GET /?data=tmp_1667bfa9bea HTTP/1.1" 200 -
127.0.0.1 - - [16/Oct/2018 10:25:14] "GET /tmp_1667bfa9bea_config.json HTTP/1.1" 200 -
127.0.0.1 - - [16/Oct/2018 10:25:14] code 404, message File not found
127.0.0.1 - - [16/Oct/2018 10:25:14] "GET /tmp_1667bfa84c5/tmp_1667bfa84c5_0.taco HTTP/1.1" 404 -
127.0.0.1 - - [16/Oct/2018 10:25:14] code 404, message File not found
127.0.0.1 - - [16/Oct/2018 10:25:14] "GET /tmp_1667bfa84c5/tmp_1667bfa84c5_0.json HTTP/1.1" 404 -
127.0.0.1 - - [16/Oct/2018 10:25:14] "GET /tmp_1667bfa9bea/tmp_1667bfa9bea_0.taco HTTP/1.1" 200 -
127.0.0.1 - - [16/Oct/2018 10:25:14] "GET /tmp_1667bfa9bea/tmp_1667bfa9bea_0.json HTTP/1.1" 200 -

from javascript console

Failed to load resource: the server responded with a status of 404 (File not found)
temporalNetworkFigure.js:132 Uncaught TypeError: Cannot read property 't' of undefined
    at temporalNetworkFigure.js:132
    at Zo._call (d3.v4.min.js:2)
    at Jo (d3.v4.min.js:2)
    at Qo (d3.v4.min.js:2)
    at Object.<anonymous> (d3.v4.min.js:2)
    at k.call (d3.v4.min.js:2)
    at XMLHttpRequest.e (d3.v4.min.js:2)
:8226/tmp_1667bfa84c5/tmp_1667bfa84c5_0.json:1 Failed to load resource: the server responded with a status of 404 (File not found)

[benmaier]

as discussed in #13