Formatting
More work on hdfs_file
pread in local_file enforces read pos >= 0
Assert seek past end of file raises IOError
Read entire file contents when requested n. bytes < 0
Raise IOError on pos < 0 in hdfs_file.seek, like a Python file
Raise on error in hdfsTell and hdfsSeek
Revert "Read entire file contents when requested n. bytes < 0"

This reverts commit 605b679c8e75b24086651db952a19c1be3641093.
Reintroduce at the Python level the logic to read to EOF when nbytes < 0
Revise write and remove write_chunk in C extension

This commit unifies the implementation of `write` and `write_chunk`
while maintaining the same functionality and interface at the Python
layer.
Handle errors in hdfs flush()
Merge pull request #22 from ilveroluca/develop

Complete error checking in hdfs_file.cc