Optimized download

Now it only ask to download for files that are on the FTP server for
sure.
Change in the input list format

Now the input file must list stations ID and not filenames. Filenames
are deducted from stations ID and the year given.
First commit

From 1977 to 2013, it uncompress all the gzip files, merge them, and
compress the merged file in a gzip.
Rename ncdcDatRetrieval_1975-2002.sh to ncdcDataRetrieval_1975-2002.sh
Merge pull request #35 from weatherTeam/Iss15/tools_ncdc

Iss15/tools ncdc