Changed some fields to tags

[pmoncadaisla]

Fields:

• method
• status
• content_type
• uri
• extension

changed to tags in order to make search faster and enable grouping.

[pmoncadaisla]

Travis tests failed, although module compilation was successful and also tests ran successfully locally:

./worker_shutdown_timeout.t ................ ok
./worker_shutdown_timeout_mail.t ........... skipped: no mail available
./worker_shutdown_timeout_proxy_upgrade.t .. ok
./worker_shutdown_timeout_stream.t ......... skipped: no stream available
./xslt.t ................................... skipped: no xslt available
./xslt_params.t ............................ skipped: no xslt available
All tests successful.
Files=330, Tests=1799, 193 wallclock secs ( 0.91 usr  0.50 sys + 18.00 cusr  5.37 csys = 24.78 CPU)
Result: PASS
+ popd
~/workspace/yoigo-thor/nginx-influxdb-module/test-build ~/workspace/yoigo-thor/nginx-influxdb-module
+ popd
~/workspace/yoigo-thor/nginx-influxdb-module

[fntlnz]

Thanks for this @pmoncadaisla - as discussed we cannot take this path for cardinality issues. Your contributions have been valuable to let us re-think about that problem. Keep them coming !