Bombs when SINCEDB_PATH and HOME are missing in env.

[jordansissel]

logstash is all like BOOM

Getting "Input thread exception", :exception=>#<TypeError: 
                        can't convert nil into String>, :backtrace=>["org/jruby/RubyFile.java:1478:in `join'", 
                        "org/jruby/RubyFile.java:1500:in `join'", 
                        "file:/usr/share/java/logstash/logstash-1.1.0-monolithic.jar!/gems/filewatch-0.3.3/lib/filewatch/tail.rb:29:in 
                        `initialize'",

The 'join' fialure is because ENV["HOME"] is nil.

[wiibaa]

You could close this issue as the changes are now in master
https://github.com/jordansissel/ruby-filewatch/blob/master/lib/filewatch/tail.rb#L43