Add two BridgeDB request graphs.

src/main/R/rserver/rserve-init.R

...main/java/org/torproject/metrics/stats/bridgedb/Main.java

.../java/org/torproject/metrics/stats/collectdescs/Main.java

src/main/java/org/torproject/metrics/stats/main/Main.java

src/main/resources/web.xml

src/main/resources/web/json/categories.json

src/main/resources/web/json/metrics.json

src/main/resources/web/jsps/reproducible-metrics.jsp

src/main/resources/web/jsps/stats.jsp