Error in curl::curl_fetch_memory(url, handle = handle) : Couldn't resolve host 'api.dropboxapi.com'

Since some time, rdrop 0.7 and now 0.8 - when I make a clean auth in session (removed all object from globalspace / cleaned cache files from project -> rm .httr-oauth) and make a succesfull auth in the session dropbox does work.

But when I save the session and then make a drop_auth(rdstoken = "data/droptoken.RDS") I get a curl error.

Error in curl::curl_fetch_memory(url, handle = handle) : Couldn't resolve host 'api.dropboxapi.com'

Here is my session info
```
> sessionInfo()
R version 3.3.2 (2016-10-31)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows >= 8 x64 (build 9200)

locale:
[1] LC_COLLATE=Slovenian_Slovenia.1250 LC_CTYPE=Slovenian_Slovenia.1250
[3] LC_MONETARY=Slovenian_Slovenia.1250 LC_NUMERIC=C
[5] LC_TIME=Slovenian_Slovenia.1250

attached base packages:
[1] stats graphics grDevices datasets utils methods base

other attached packages:
**[1] curl_2.8.1** shinydashboard_0.6.1 tm_0.7-1 NLP_0.1-11
[5] stringr_1.2.0 timeDate_3012.100 quantmod_0.4-10 TTR_0.23-2
[9] xts_0.10-0 zoo_1.8-0 cluster_2.0.5 fpc_2.1-10
[13] formattable_0.2.0.1 wordcloud2_0.2.0 DT_0.2.10 dygraphs_1.1.1.4
[17] shinyjs_0.9.1 shinyBS_0.61 quanteda_0.9.9-65 bcrypt_1.0
[21] sqldf_0.4-11 RSQLite_2.0 gsubfn_0.6-6 proto_1.0.0
[25] shiny_1.0.5 data.table_1.10.4 **rdrop2_0.8** installr_0.18.0

loaded via a namespace (and not attached):
[1] assertive.models_0.0-1 bit64_0.9-7 httr_1.3.1
[4] rprojroot_1.2 prabclus_2.2-6 assertive.datetimes_0.0-2
[7] tools_3.3.2 backports_1.1.1 R6_2.2.2
[10] DBI_0.7 lazyeval_0.2.0 colorspace_1.3-2
[13] trimcluster_0.1-2 nnet_7.3-12 assertive.data_0.0-1
[16] assertive.reflection_0.0-4 bit_1.1-12 chron_2.3-50
[19] assertive.properties_0.0-4 assertive.files_0.0-2 slam_0.1-40
[22] diptest_0.75-7 scales_0.5.0 DEoptimR_1.0-8
[25] mvtnorm_1.0-6 robustbase_0.92-7 digest_0.6.12
[28] rmarkdown_1.6 assertive.numbers_0.0-2 htmltools_0.3.6
[31] htmlwidgets_0.9 rlang_0.1.2 assertive_0.3-5
[34] jsonlite_1.5 mclust_5.3 magrittr_1.5
[37] modeltools_0.2-21 Matrix_1.2-7.1 Rcpp_0.12.12
[40] munsell_0.4.3 stringi_1.1.5 assertive.base_0.0-7
[43] yaml_2.1.14 MASS_7.3-45 flexmix_2.3-14
[46] plyr_1.8.4 grid_3.3.2 blob_1.1.0
[49] parallel_3.3.2 miniUI_0.1.1 lattice_0.20-34
[52] assertive.code_0.0-1 knitr_1.17 tcltk_3.3.2
[55] assertive.sets_0.0-3 codetools_0.2-15 stats4_3.3.2
[58] fastmatch_1.1-0 evaluate_0.10.1 RcppParallel_4.3.20
[61] httpuv_1.3.5 gtable_0.2.0 openssl_0.9.7
[64] kernlab_0.9-25 assertive.strings_0.0-3 ggplot2_2.2.1
[67] mime_0.5 xtable_1.8-2 assertive.types_0.0-3
[70] assertive.data.uk_0.0-1 class_7.3-14 tibble_1.3.4
[73] memoise_1.1.0 assertive.matrices_0.0-1 assertive.data.us_0.0-1
```

Start with the reported difference between fresh authentication and drop_auth(rdstoken = "data/droptoken.RDS"), using the provided R and rdrop2 session information to reproduce it. Compare both authentication paths and verify that loading the saved token completes without the curl error for api.dropboxapi.com.

Written by the indexing model from the issue text.