Handle network timeouts gracefully

[pridkett]

Network connectivity errors cause hard crashes. This should be handled more gracefully.

11:46:14 [main] ERROR n.w.r.github.v3.WatcherMinerV3 WatcherMinerV3.java:44 - IOException in getting watchers for repository: rstacruz/js2coffee
java.io.IOException: Bad Gateway
        at org.eclipse.egit.github.core.client.GitHubClient.createException(GitHubClient.java:511) ~[org.eclipse.egit.github.core-1.3.0-SNAPSHOT-WAGSTROM.jar:na]
        at org.eclipse.egit.github.core.client.GitHubClient.get(GitHubClient.java:643) ~[org.eclipse.egit.github.core-1.3.0-SNAPSHOT-WAGSTROM.jar:na]
        at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source) ~[na:na]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.6.0_22]
        at java.lang.reflect.Method.invoke(Method.java:616) ~[na:1.6.0_22]
        at net.wagstrom.research.github.v3.ThrottledGitHubInvocationHandler.invoke(ThrottledGitHubInvocationHandler.java:61) ~[github-0.2-SNAPSHOT.jar:na]
        at $Proxy7.get(Unknown Source) ~[na:na]
        at org.eclipse.egit.github.core.client.PageIterator.next(PageIterator.java:173) ~[org.eclipse.egit.github.core-1.3.0-SNAPSHOT-WAGSTROM.jar:na]
        at org.eclipse.egit.github.core.service.GitHubService.getAll(GitHubService.java:151) ~[org.eclipse.egit.github.core-1.3.0-SNAPSHOT-WAGSTROM.jar:na]
        at org.eclipse.egit.github.core.service.GitHubService.getAll(GitHubService.java:135) ~[org.eclipse.egit.github.core-1.3.0-SNAPSHOT-WAGSTROM.jar:na]
        at org.eclipse.egit.github.core.service.WatcherService.getWatchers(WatcherService.java:89) ~[org.eclipse.egit.github.core-1.3.0-SNAPSHOT-WAGSTROM.jar:na]
        at net.wagstrom.research.github.v3.WatcherMinerV3.getWatchers(WatcherMinerV3.java:42) ~[github-0.2-SNAPSHOT.jar:na]
        at net.wagstrom.research.github.GitHubMain.main(GitHubMain.java:145) [github-0.2-SNAPSHOT.jar:na]
        at net.wagstrom.research.github.Github.run(Github.java:86) [github-0.2-SNAPSHOT.jar:na]
        at net.wagstrom.research.github.Github.main(Github.java:51) [github-0.2-SNAPSHOT.jar:na]
Exception in thread "main" java.lang.NullPointerException
        at net.wagstrom.research.github.BlueprintsDriver.saveRepositoryWatchers(BlueprintsDriver.java:1380)
        at net.wagstrom.research.github.GitHubMain.main(GitHubMain.java:145)
        at net.wagstrom.research.github.Github.run(Github.java:86)
        at net.wagstrom.research.github.Github.main(Github.java:51)