Illegal char <:> in the log filename causes failure

```
Reproduce:
1. Make a barebones test
2. Run it on Windows

This exception is thrown, obviously logger is trying to create file with
HH:MM:SS time in filename:

1) Error injecting method, java.nio.file.InvalidPathException: Illegal char <:>
at index 41:
C:\Users\MYUSERNAME\.caliper\log\2015-03-06T20:39:05.116Z.8176cc24-a129-45c6-9a7
e-262c4f71e3e9.log.lck
at com.google.caliper.config.LoggingConfigLoader.loadLoggingConfig(LoggingConfigLoader.java:56)
at com.google.caliper.config.ConfigModule.configure(ConfigModule.java:31)
while locating com.google.caliper.config.LoggingConfigLoader

Version: 1.0 beta from Maven
OS: Windows Home Premium 7x64

```

Original issue reported on code.google.com by `ja.mar...@gmail.com` on 6 Mar 2015 at 9:00

Attachments:
- [TestWindowValidSpeed.java](https://storage.googleapis.com/google-code-attachments/caliper/issue-306/comment-0/TestWindowValidSpeed.java)