Exclude files from cache based on name

[siddharthab]

The current logic to assume that files are meant for small random reads
if the first read to them has a non-zero offset, assumes the absence of
file headers at the beginning of the file, and/or the absence of magic
number checks.

The new option to specify such files by regular expression pattern will
allow the users to mark such files as random access only, even when
their headers are fetched first.

Some organization cleanup has also been performed that moves the
cacheFileForRangeRead option to inside the CacheHandler instead of
passing it through as function arguments.

[siddharthab]

Please let me know how you would like me to run the integration tests, etc. manually for this PR.