Log Message:
Updated jsoncpp to 1.7.7.

Changes in 1.7.7:
    At the suggestion of Peter Spiess-Knafl, we will bump the
    SOVERSION independent of the MAJOR.MINOR.MICRO version, in case
    we break binary compatibility.

Changes in 1.7.6:
    Prevent possible SEGV. (Thanks to @ngg.)
    Add RPATH for OSX libs. (Please let us know if this causes a problem.)

Changes in 1.7.5:
    Fix locale for decimal points
        Plus a fix for Android
    int64_t for 64-bit integers
    Optionally suppress space after comma
    Avoid null for empty stringValue
    Fix null ctor/dtor, using a "Meyers Singleton"
        Thanks to @marklakata and @BillyDonahue in #488 in #490.