Fixed killall problem in parsing "jps -l"
Fixed killall problem in parsing "jps -l"

Summary:
Buck killall subcommand identifies the target java process to kill using `jps -l`. `jps -l` command produces the list of java processes formatted as "<pid> <classname>" per line, but in some cases(*) it doesn't follow the formatting rule, which causes the killall subcommand to fail to parse the output. This change makes the parser more robust against it.

(*) `jps -l` command doesn't follow the formatting rule when:
- using an old version of java8
- some java processes' cache (/tmp/hperfdata*) remains for unknown reason despite they already died
- Java processes which are launched not as `java Main` (e. g. `idea`) are shown with only PID without main class name (this is handled already in the current Buck version)

Reviewed By: lebentle

fbshipit-source-id: 6b67744a29306ce77a4e204a3bf9fd29d8015c54

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